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Research into possible cures for the New Plague created the Forced Evolution Virus, which was further developed in an attempt to create a transmittable genetic-engineering virus -- in effect, infectious evolution.ZAX 1.2

The Forced Evolutionary Virus, or FEV, is an artificial virus created by West Tek's NBC Division. Its ability to force changes in both the genotype and phenotype and ease of modifying it for whatever purpose desired made it one of the most important mutagens in the wasteland, harnessed by different organizations and individuals for their own purposes both before and after the Great War. FEV exists in various forms across all of the Fallout games, mainly to serve the goals of the various antagonists. It was through the FEV that the Master made his race of super mutants and how the Enclave meant to commit genocide on humanity.

There are multiple strains of FEV in existence, tailored for the specific goals of these entities. The strain responsible for creating regular super mutants is called FEV-2[1][2][3] and represents the pinnacle of pre-War research into the virus. A different FEV strain is the source of the super mutants infesting the Capital Wasteland, intellectually inferior to their West Coast cousins. Other strains created the monsters of Appalachia and the distinct super mutants of the Commonwealth. The Institute's strain also served the basis for their eventual generation 3 synths.

Beyond direct mutations, FEV had other effects: The ease with which FEV could be synthesized and used to force mutations, resulting in many horrors being unleashed on the wasteland, was one of the causes for the Brotherhood of Steel's policy of technological containment.[4]



Fo1 Dipping

The standard dipping method used by the Unity, resulting in a severe overdose of the virus.

The Forced Evolutionary Virus is a megavirus, transmissable through direct contact or injection.[5][6] It cannot infect individuals through airborne transmission from an already infected individual.[6] In most cases, it is seen in the form of a green liquid contained within large vats,[7] but it can also be administered via an aerosol solution.[8] It has a strong structure: A protein sheath reinforced by ionized hydrogen, allowing it to absorb neutrons without being radioactive, making it immune to radiation.[5]

The purpose of the virus is to correct its host's DNA, creating a theoretically better specimen. As FEV is a shifting-absorptive virus, it copies DNA patterns not unlike RNA, storing them in exons and combining them with FEV. The virus is pre-programmed with corrected DNA patterns appropriate to the species (at least theoretically), and the DNA is merged with them through FEV's own recursive code. The resulting genetic code is then re-injected into the host cell in typical viral infectious fashion, regenerating its DNA. While the process is theoretically sound, FEV partially relies on the host's DNA and includes portions of its code when re-injecting the cell, which can cause unpredictable effects.[9][10]

Furthermore, the effects also depend on the method of exposure and levels, as FEV does not seem to replicate within the host's body and its effects are limited by the size of the sample: While the iconic super mutants are created by exposing humans to an amount considered to be a severe overdose,[3] by immersing them entirely in a vat full of FEV,[11] and super mutant transformation can also occur through long term exposure to low concentrations of FEV (which is the source of the second generation super mutants, Enclave slaves doomed to work at Mariposa),[12] direct injections produce limited, controlled mutation in a given area. The Master's experiments included injecting FEV directly into various areas of the brain to induce psychic ability, with some success.[13][14]


When administered to a genetically viable individual, the infection process will rewrite portions of the host’s DNA, causing accelerated mutation, usually leading to conspicuously complete DNA strands[3] and recursive growth due to the FEV's own patterns.[10] The process is generally extremely painful, depending on levels and method of exposure. Some strains cause extreme pain and body deformation upon overdose and long-term exposure.[15] Others cause rapid physical changes in a short period of time and excruciating pain that results in permanent mental damage in most subjects.[16] In non-viable individuals, such as those with significant genetic damage due to radiation sickness or exposure to other form of FEV,[17] the mutation forced by FEV's recursive growth patterns can lead to massive overhauling of the body's systems, organ failure, and expiration.[10]

The actual effects of this process largely depend on exactly what DNA is programmed into FEV. It is modifiable by design, and while the initial design focused on creating super soldiers, it can be used as a general purpose mutation vector. For example, the Master modified FEV-2 to only bond with human glyco-proteins, and the Enclave used that functionality to turn it into FEV Curling-13, a potent toxin that would target exclusively humans (mutated or not). The whole process took only a few years, and in the meantime, the Chemical Corps also experimented with modified FEV to create Frank Horrigan.[18] On the other side of the continent, Weston Lesko experimented with FEV as a mutagen for the purposes of genetic recoding, to reduce giant ants to their original size. The unpredictable nature of FEV, however, resulted in a disaster that claimed Grayditch.[19][20]

One common effect of FEV is continuous augmented cell growth, as FEV causes constant regenerative updates to cell DNA. In humans, this results in a mitosis rate at least 15% faster in super mutants, which also grants an extended lifespan. Theorized to be a 10% extension by post-War analyses,[3] FEV can actually render host organisms immortal: Augmented growth offsets cell death and the constant regenerative updates prevent genetic damage responsible for aging. It also prevents damage from ionizing radiation and genetic diseases.[21][22] However, there is a potential side effect: The same mechanism can also cause sterility, if FEV misidentifies gametes as damaged cells during the mutation process. In this case, FEV would "repair" the "damage," making these cells permanently non-viable.[23]

It is not clear if and how FEV affects sperm. However, in any species with a non-renewable pool of oocytes (i.e. whose female members are born with a finite amount of cells that can mature into fertile ova), FEV would target this pool and "fix" it. As such, even if spermatogenesis resumes in males, producing viable sperm,[24][Non-game 1] this sperm would be unable to merge with the "fixed" ovum, and any attempt to reproduce would fail.[25] This was confirmed with FEV-2 super mutants created by the Master: FEV rendered them unable to reproduce with any other creature.[3][23] This fact went unnoticed for years, as FEV-2 did not destroy primary sexual organs, and the effects took place on a cellular level.[2]


FEV was designed to introduce permanent changes to the host, and as such did not retain unaltered original copies of the subject's DNA. It could only theoretically be "cured" by a virus that re-infected the subject with its original DNA like FEV did, which technically would be a second forced mutation, rather than a cure. Secondly, there was no known way to remove the FEV from the host before the Great War.[26] While the Enclave developed an inoculation that prevented its version of FEV from affecting the subject, which could be administered by injection or aerosol exposure, it only affected its particular version of the toxin and was not a cure.[27]

A potential cure was created by The Institute. Its continued experiments with FEV after the Great War iterated on the original design. In the late 23rd century, Dr. Brian Virgil confirmed the hypothesis, creating a retroviral serum capable of reversing his transformation into a super mutant (which was necessary to escape the Institute's underground facility). The week-long mutation was not a cure, but a secondary mutation into a human, with the genetic resequencer resulting in side effects, such as restoration of his hairline and an increase in muscle mass.[28][29] It was a significant advance, but was specifically designed to work with the Institute's strain of FEV, with any possibility of generalizing the formula requiring years, if not decades of additional research.[30]

Virus strains[]


FEV research was spun off from the Pan-Immunity Virion Project in March 2075, two years into the initiative. Initially seen as a possible cure for the New Plague and Chinese bioweapons, it was noted that the virion could become a transmittable genetic-engineering virus, allowing for infectious evolution.[31] Using batch 10-011 as basis, provisionally renamed Forced Evolutionary Virus, it still used the quad-helix structure of PV, and initial experiments on single-celled organisms were promising: They demonstrated increased immunity to infection and radiation. Chloroplasts were unaffected by the virus, causing experiments on plants to be cancelled.[32]

Subsequent experiments with flatworms demonstrated that FEV affected organisms in real time: Flatworms increased their size by 28% within hours and demonstrated resistance to 39 separate viral contagions. Each sample also procreated successfully (though only asexually), retaining the quad-helix structure. Experiments on insects showed less success and were indefinitely postponed.[32]

On vertebrates such as white mice, FEV showed even greater effects: Growth began within hours, stabilizing after 9 days, producing the greatest increases in striated muscle tissues and organs like the liver, heart, and kidneys. Increased intelligence was also noted, completing mazes in half the time of the control group. Further experiments on rabbits confirmed that brain activity immediately increased 3.2 seconds on average after injection, alongside the usual increase in size. FEV primarily affected dendritic connections, in the limbic system and frontal cortex (which appeared tied to increased aggression and posturing).[32]

In 2076, experiments began with batch 11-011, modified to improve the mitotic cycle efficiency. Experiments on raccoons demonstrated the usual size increase, with behavioral tests confirming increases in intelligence and manual dexterity by 19 points on the Schuler-Kapp index. FEV allowed several subjects to actually escape containment. Further modifications spliced into FEV and provided by Barnett's advisory team, identified as batch 11-101a, resulted in FEV that caused immediate growth, increased final size, and high aggression, but did not affect the intelligence of the dogs used as test subjects. 92 allele pairs from the batch were selected for recombination with batch 11-011.[32]

The crossover took four months, resulting in batch 11-111. When used on chimpanzees, it resulted in unprecedent growth and immunity to chemical and radiological agents: Deliberate attempts to induce cancers failed. The subjects exhibited increase aggression, forcing them to be isolated, with two of the fifteen suffering epileptic seizures leading to their death. By January 2077, the military elected to relocate all assets to the newly built Mariposa Military Base in central California, to commence human testing on human subjects, despite objections from West Tek staff.[32] FEV was considered as nearing completion, demonstrating consistent size and muscle density increases by approximately 60% and potential intelligence increase by 200%.[33] The potential to create super soldiers was tremendous.[34]

It is not entirely clear when FEV was divided into FEV-1 and FEV-2. At the onset, FEV was simply a variant of PV, named without a discriminator, and both names were used interchangeably. Batch identifiers suggest a logical progression: 10-011 was the first version of FEV (corresponding to 2-3 in decimal), derived from FEV, with 11-011 (3-3 in decimal, in January 2076) used as basis for what would be FEV-2.[32] The term FEV-2 is exclusively used to identify the strain used at Mariposa, further modified by the Master and forming the basis of all subsequent FEV variants.[35]



Harry; a first generation super mutant exposed to the FEV-2 strain.

FEV-2[35] is the virus strain originating in the Mariposa Military Base and responsible for many mutations across the New West, including New California and Mojave Wasteland regions is FEV-2.[3][2] It is responsible for the creation of a diverse range of creatures, including psykers, super mutants, centaurs and floaters, primarily at the behest of the Master and the Unity. Although initially used as a generic purpose mutation vector for gene splicing,[36][Non-game 2] the Master eventually modified FEV-2 to bond exclusively with human glycoproteins.[18] This version of FEV-2 created both the first and second generation super mutants, the latter when the Enclave excavated the military base, after it was destroyed by the Vault Dweller in 2161.[12]

In humans, physical and observational changes brought upon by the FEV-2 strain are substantial. The Nightkin, the best of the first generation super mutants were created from human subjects with a limited exposure to radiation or mutated FEV, such as those from Vaults within the region.[17] For the most stunning mutations to occur, a human subject would be left submerged within a vat of FEV-2 for 24 hours, allowing them to receive a severe overdose of the virus and complete the super mutant transformation. Each batch would contain up to six individuals, not separated by biological sex. Over 23,800 batches of FEV were processed by the time the Vault Dweller destroyed the vats.[37][3]

The resulting mutants were stunning creatures. A first generation super mutant autopsied by Head Scribe Vree had a height of 3.2 meters, and weighed 363.21 kilograms. Out of the total mass, 77.41% was accounted as muscle mass, with 10.23% of bone mass, 3.02% of fat mass and 9.34% of tissue mass. The skin color was described to be predominantly gray with tints of green under the lighting system of the Lost Hills bunker, while the skin's composition had reportedly become tougher, dry, and sometimes flaky, which would make it more resistant to trauma.[3][38] Despite this resistance to trauma, completely destroyed tissue is unable to heal and will thus result in scarring or organ loss depending on the severity and location of the damage.[39] Keratoses, benign non-cancerous growths, could also occur on the skin.[40]

On a genetic level, cells underwent cellular division at an increased rate, with mitosis occuring 15% faster than that of an average human. The mutant also had a highly similar cellular and genetic structure to the average human. All recessive genes for ailments appeared to have been eradicated from the mutant's body, with RNA strands appearing to have been manipulated to allow for a greater transmission of signals and bring out the best possible combination. The mutant was also rendered sterile by the FEV exposure.[3]

The FEV-2 strain has a small chance of increasing intelligence, with most retaining their intellect prior to their exposure. Only a minority of remaining individuals may experience an increase,[Non-game 3] with the rest typically experiencing a loss by 30%.[3][41] However, those who have received a prolonged exposure to small amounts of the strain, such as the second generation super mutants, are noted to have a significantly worse intelligence than first generation super mutants, unable to think for themselves, often falling to the influence of others.[42][43]

Psyker program[]

Main article: Psyker

Apart from transforming humans into super mutants, the Master and his staff experimented with FEV by injecting it into the brains of subjects (usually the pineal gland, but also the amygdala or medulla), triggering changes in brain chemistry.[44] These experiments had limited success: four extremely powerful psykers were created, theoretically capable of wiping out the human race.[Non-game 4] However, the same changes that increased psychic ability also resulted in terminal insanity, forcing them to be sequestered and nullified with specialized equipment to prevent them from harming themselves or others.[13]

EEP strain[]

Uncle Leo

Uncle Leo; a super mutant exposed to the EEP strain.

The derivative FEV strain used at Vault 87 retains the recursive growth patterns characteristic to FEV, but has a different effect, which may be also linked to how infection was performed in the labs. Testing began in 2078,[Non-game 5] where test subjects were exposed a single time to FEV in isolated chambers where the virus was deployed with an airborne aerosol. Phenotypical changes occur within three days and include increased muscle mass, changes in skeletal structure, and atrophy of sexual characteristics, both primary and secondary (including body hair). At ten days, skin pigmentation becomes a mixture of yellow and green, while its thickness and resistance to radiation and other environmental hazards rapidly increases.[Non-game 5][45]

However, a key problem was that the mutation did not stop. Within fourteen days of initial exposure, test subjects regress to an almost feral state, exhibiting extreme aggression at every non-mutant. While some semblance of cognition is retained, exhibited by the ability to speak, operate machines and use basic tactics in combat, super mutants of this type are typically characterized by profound intellectual decline.[45] This result is most likely brought upon by the same factor as with FEV-2: Damage to existing neural patterns caused by rapid changes in the phenotype. The effects typically cause significant damage to long term memory, again, a shared characteristic.[46] The traumatic nature of the transformation is also a factor. The excruciating pain that accompanies it can and will cause the subjects to become insane.[16][Non-game 5]

Another unforeseen side effect is that the unfinished virus strain codes the body for continued growth. If a super mutant of this type eludes death for prolonged periods of time, they may become a considerable threat, reaching the size of a small building.[Non-game 5]

Institute strains[]


Strong; a super mutant exposed to one of the Institute's FEV strains.

The super mutants of the Commonwealth are a completely different strain from others. While they possess the imposing musculature and resilience of the former, they have an average level of intelligence on par with examples of the latter. They are capable of following a chain of command, erecting fortifications,[47] and even setting up traps and ambushes - such as at Trinity Tower, where Fist deliberately used Rex Goodman as bait to lure humans and weed out the weak super mutants among his host. They are also capable of speaking like normal humans, unlike their practically feral brethren from the Capital Wasteland, and consider themselves the superior race of the Commonwealth.[48] All super mutants of the Commonwealth are products of the Institute's experiments into FEV using the abducted Commonwealth wastelanders above ground. These experiments were the base work used to progress their synths from mechanical construction to a new frontier using human DNA as a base to construct synthetic humans. The Commonwealth super mutants share a similar morphology with the super mutants derived from Appalachian West Tek's experiments on the Huntersville strain, but is unknown if the two strains are closely related.

Main article: Generation 3 synth

A third generation synth Courser.

The most advanced synthetics created by the Institute are fundamentally different from their predecessors. Despite the sequential numbering, they are unrelated to their mechanical counterparts, in fact. They are derived from Shaun's pre-War DNA extensively modified using the Institute's own research into the Forced Evolutionary Virus, combining the advantageous adaptations encoded into FEV with the versatility of the human body shape. This allowed the Institute to create a variety of synths of varying races and appearances despite the base DNA coming from only one source. They are the result of nearly five decades of research, from 2178 to 2227.[49][50][51][52]

Third generation synthetics are unlike humans and some liberated synths do not consider themselves human at all. The reasons for this are multiple, and chief among them is the synth assembly process.[53] Other reasons include the fact that gen 3 synths may not require sleep to function properly, are more resistant to disease, and may not require the intake of food or water to generate energy for their bodies.[54][55]

Huntersville strain[]


Grahm; a super mutant exposed to the Huntersville strain.

The Appalachia super mutants were created shortly before the Great War, when the local West Tek facility contaminated the river water that ran through Huntersville with a unique strain of FEV as part of an experiment.[56]

Huntersville super mutants are similar to those of Mariposa and the Institute: they have green skin, highly developed musculature, and they are smart enough to build improvised armor from waste or scrap. Although they do not use large fortifications like the Vault 87 or the Institute strain super mutants, they can occasionally build small fortresses or take entire buildings. They possess the same level of strength and durability and are intelligent enough to engage in prolonged battles with other groups, such as during the Battle of Huntersville or their assault against the Brotherhood First Expeditionary Force at Fort Atlas. Like Vault 87 and Institute super mutants, Huntersville super mutants can develop into behemoths, which can be seen guarding their main bases. The majority of the super mutants will attack the player character, but some super mutants like Grahm are friendly and will even trade with humans.

Related projects[]

Appalachian experiments[]

Experiments with recombinant strains of FEV at the West Tek Research Center in Appalachia produced numerous failed mutations, with two exceptions:

  • FEVS-006443 from October 14, 2077, a Phase 2 combination strain that combined traits that resembled a number of different species. The results were considered disturbing by the scientists but provided valuable insights as to the capability of recombinant FEV. Notable changes included a number of ocular organs along the enlarged upper torso, the second set of arms ending in clawed digits, and a large sickle-shaped claw on each inner toe. The living, stable, and functioning subject was sustaining itself normally (a major accomplishment for the program) and was planned for release in Huntersville after the subsequent experiment matured.[57] The mutant was never returned to the area until January 3, 2078, when it escaped containment and the facility. The mutant procreated, leading to the emergence of snallygaster mutants across Appalachia.[58]
  • FEVS-006458 from October 23, 2077. Tweaking the snallygaster strain, researchers tweaked the genome, producing a giant that shattered the containment unit, but was otherwise stable (excepting the absence of a discernible head). The mutant was sedated and transported off-site, with the Great War sidetracking the convoy and allowing the Grafton monster to escape into the wild.[59]

Albino mole rats[]

Main article: Albino mole rat

Before the destruction of the Glow, lab rats were exposed to FEV. In the turmoil of the facility's destruction, they escaped into the wasteland. Similar to the Enclave's later experiments with deathclaws, these two unique rats gained intelligence and ability to talk, along with a long lifespan.[60]

FEV Curling-13 strain[]

Main article: FEV Curling-13

Based on the original FEV-2 recovered by the Enclave at the Mariposa Military Base's ruins, FEV Curling-13 was a viral agent tailored to reach maximum levels of lethality with minimal exposure levels required to achieve the result. It was being developed under the direction of Lieutenant Colonel Dr. Charles Curling of the Chemical Corps since 2236, to provide the means for the Enclave's genocide. Just a .0001% aerosol solution exposure was enough to kill Arroyo villagers in under one hour, as massive hemorrhaging and inflammations start, leading to a complete failure of the victim's organs within sixty minutes. A significant radiation-induced mutation may thus be beneficial – humans with a lower radiation count suffer a much worse fate. Unmutated Vault 13 dwellers exposed to the virus experienced subdermal hemorrhaging and convulsions within sixty minutes of exposure, but their agony lasted much longer – 14.5 hours on average. No test subject survived the tests on Control Station Enclave.[8]

In the event of worldwide release, only humans and human-based mutants would be eradicated, however – FEV was engineered to bond only with human glycoproteins, leaving other animals and plant life alive and unaffected.[18] FEV Curling-13 is also unique in that it is the only known FEV strain for which an inoculation was developed that granted total immunity from its effects,[27] though required several iterations before it was perfected. Some test subjects, like Enclave Vice-President Daniel Bird, suffered permanent brain damage after volunteering.[61]

Modified FEV Curling-13[]

Main article: Modified FEV

A modified strain of FEV developed by John Henry Eden, based on the earlier FEV Curling-13 strain used by the Enclave in 2241, only now it was designed to be placed into the Project Purity water purification system.[62] According to President Eden, this modfied strain will eradicate super mutants, ghouls, and all other "unclean" citizens, namely anyone who had been born in the wastelands and exposed to radiation or other mutational effects from birth.[63] The only people who would survive the infection are dangerous radiation level free humans and humans who were born in the Vaults.[64]

In the add-on Broken Steel, if the Lone Wanderer had chosen to contaminate the purifier with the modified FEV, what President Eden claimed is confirmed to be accurate and the FEV diffused in water completely lethal. The medical facility of every city in the Capital Wasteland (except Tenpenny Tower and Paradise Falls) is filled with new patients dying from FEV infection. These new patients hold their stomachs and repeat dialogue along the lines of, "it burns on the inside." According to both Doctor Preston and Doctor Barrows, the FEV specifically targets the immune system of infected individuals, which in turn makes them vulnerable to other diseases. This occurs in both humans and ghouls, despite the latter's immunity to most diseases.[65][66] Along with affecting the immune system, the modified FEV severely weaken individuals both physically and mentally until it simply kills them.[67] The modified FEV is also completely undetectable by any kind of test meaning there is no possible way to screen water that has been infected as it only comes back as clean, purified water.[68][69]

The FEV is contained to only those that have ingested infected water as the transmission of FEV is impossible from physical contact or bodily fluids. In Rivet City, Preston comments that they are burning the corpses just to be safe.[65] The spread of the modified FEV is contained to only bottles of Aqua Pura and the Tidal Basin for now. However, eventually, the spread of the FEV infected water will spread from the Tidal Basin and affect all water in the Capital Wasteland.

Intelligent deathclaws[]

Main article: Intelligent deathclaw

In 2235, the Enclave began experiments on captive deathclaws to create expendable shock troops for their use, continuing the pre-War project.[Non-game 6] The recovery of FEV from Mariposa allowed them to create a tailored mutagen that increased the intelligence of deathclaws after localized injections, making them capable of understanding and following complex commands, as well as communication. The resulting modification overshot the project goals, giving them human-level intelligence, erudition, and most importantly, morality. Realizing that they would be exterminated if that was discovered, Gruthar instructed his pack to play dumb until they were deployed to Vault 13. Although the Enclave intended to use them as deterrence, the deathclaws formed a commune instead, deserting their mission. Not all deathclaws were equally blessed with intelligence and some experienced further changes, including a gray skin and a bobtail.[70]

All intelligent deathclaws were exterminated by a task force headed by Frank Horrigan, mopping the project up.[71]

Fire ants[]

Main article: Fire ant
Fire ant

FEV was synthesized and used by Dr. Weston Lesko in the Capital Wasteland around 2277 in an attempt to return giant ants to their normal size through genetic manipulation. His ambition was to reduce their size exponentially over the course of several generations. However, an error in the synthesis process created a virus that left the ants' size unaltered but altered their venom sacks to produce a flammable liquid that they can aerosolize, project, and ignite with a spark generated by clicking mandibles. The resulting pyrosis, as he calls it, turns them effectively into walking flamethrowers.[72][73][74]

History of the FEV[]

A long story. FEV... a virus with an even longer story...Father Elijah, Dead Money

The Forced Evolution Virus originated from the Pan-Immunity Virion Project, a project originally dedicated to discovering a cure for the New Plague, was established in September 2073 in response to aggressive use of biochemical weapons by China. In order to combat the newest biological weapons, the decision was made to create a viral defense that would alter uninfected DNA to render it immune to standard viral infection.[75]

The last attempt to continue the PVP line of experimentation was the Greenhouse Initiative in August 2075 at the newly established Appalachian branch, which attempted to use mutations to create edible plants and vegetation that could greatly increase food production and combat the shortages that led to the food riots rocking the country.[76] The town of Huntersville was selected as the test site, resulting in an economic boom.[77] Although the company would purchase test rights from local farmers as late as December 2075, the project was at an end.[78]

Batch 10-011 and the beginning of FEV[]

The history of the FEV starts with Pan-Immunity Virion batch 10-011, renamed as the Forced Evolutionary Virus (FEV) and used in further research. The key difference was that instead of Pan-Immunity Virion's quad-helix DNA structure, the batch became a shifting-absorptive virus. This was a deliberate choice by Major Barnett, who considered the unwanted side effects of the quad-helix structure to outweigh the benefits of replicative stability afforded by the design.[32]

The first experiments took place in March 21, 2075 on single-celled organisms. While their base metabolism appeared unchanged, their immunity to infection and radiation exceeded all earlier expectations. Research on FEV effects on plants proved unsuccessful. The next stage included flatworms. Infected on May 9, 2075, they exhibited a 28% increase in size and resistance to 9 separate viral contagions within hours. The new DNA structure was successfully passed to progeny, though only asexual reproduction was possible.[32]

June 30, 2075, saw the next stage of experimentation: several lab strains of white mice have been infected successfully with FEV. Within hours they exhibited increased growth, stabilizing at a 31% size increase after nine days. The most increase in size occurred in striated muscle tissue and certain internal organs, including the liver, heart, and kidneys. An increase in intelligence was also noted, allowing mice to run mazes in less than half the time required by normal mice.[32]

The final experimentation with FEV batch 10-011 occurred with rabbits. On November 9, 2075, 218 rabbits were infected, half of which were implanted with electrodes to monitor changes in EEG activity. Increased electrical activity was noted 3.2 seconds after infection, accompanied by the typical increase in size. A new effect was noted, namely an increase in aggression and posturing, particularly among males. Dissection of the brains showed an increased dendritic connection, particularly in the limbic system and frontal cortex (areas responsible for behavior, senses and higher mental functions).[32]

Batch 11-011 and nationalization[]

On January 6, 2076, West Tek was effectively nationalized after military units deployed to corporate facilities across the United States in the interest of national security.[79] Experiments continued with Batch 11-011. The new virus batch featured improved mitotic cycle efficiency by a factor of 43%. As part of the test, 53 raccoons were infected with the new strain on January 26, 2076. Along with the expected size increase, behavioral tests confirmed an increase in intelligence and manual dexterity by 19 points on the Schuler-Kapp index. Unfortunately, subjects escaped confinement and had to be hunted down. Two pairs were unaccounted for.[32][Non-game 7]

In February, the West Tek facility in Appalachia joined the FEV research effort, ordered to begin human experimentation in order to push FEV to its practical limits, in what was dubbed the Super Mutant program. Due to the virulent nature of the virus and its unpredictability, the facility's objective was to identify and isolate viable FEV strains through a variety of methods. The most important of these was the introduction of one of the FEV strains to the water supply of Huntersville, to observe the effects of long-term low-level exposure. The experiment began in February 2076, providing valuable research data for the project.[80]

Further development occurred after several new gene sequences, supplied by Major Barnett's advisory team, were spliced into FEV batch 11-011. Designated batch 11-101a, this batch was used to infect 23 dogs of pure and mixed breed on May 13, 2076. The results included nearly immediate growth, accompanied by increased aggression and no notable increase in intelligence. All subjects were terminated after 14 weeks of study. 92 allele pairs were chosen for splicing with batch 11-011.[32]

Batch 11-111 and further human research[]

The new hybrid batch was designated 11-111. On October 4, 2076, it was used to infect 15 chimpanzees. Growth and immunity levels were unprecedented: attempts to induce cancers through radiological and chemical agents were not successful. Increased aggression led to isolating the subjects by the science team, while violent epileptic seizures caused two subjects to expire. The rest was terminated after all data was mined successfully.[32]

Despite protests from the science team, on January 7, 2077, FEV research in California was transferred to the Mariposa Military Base [32] to continue under the lead of Leon Von Felden and Robert Anderson. Batch 11-111 has been chosen as the basis for further development through human experimentation. The batch offered a near 100% success rate on lab animals, granting an approximately 60% increase in size and potential 200% intelligence increase. It was the perfect basis for mass-producing super soldiers, and would eventually be identified as FEV-2.[75]

The Appalachian branch continued its experimentation by pushing FEV to its practical limits and experimenting with recombinant strains. The experimental strains resulted in the creation of many unsustainable forms: FEVS-005938 tested on January 13, 2077, rendered the subject unable to breathe,[81] FEVS-006186 from April 30 converted the subject into a mass of retinal tissue,[82] FEVS-006309 from July 12 produced canines that pierced the brain stem through unrestrained growth,[83] and FEVS-006378 from July 12 was biologically stable, but the hyperactive nervous system subjected it to constant traumatic pain and led to self-termination.[84] The team had more luck with strains FEVS-006443 (October 14) and FEVS-006458 (October 23) that created stable mutations that would become the snallygaster and the Grafton monster respectively after their escape into the wild.[57][59]

Another research effort was set up by the Vault-Tec Corporation in Washington, D.C. Vault 87 was established as an independent research center for Dr. Wayne Merrick, cooperating with the team at Mariposa. Despite his efforts, he was unable to improve batch 11-111 enough to reach satisfactory effects. Humans subject to his strains produced in the Vault 87 labs exhibited superior physical developments, such as increased size, strength, and endurance to environmental factors, but were also characterized by significant mental disability and extreme aggression to non-mutants.[45]

Compared to Merrick's efforts and Appalachian experiments, the science team at Mariposa reached a full success. They succeeded in creating the FEV-2 strain, able to create powerful super-soldiers, exhibiting superior physical prowess, resistance to combat damage, aging, and disease, as well as a negligible loss of intelligence.[3] In certain cases, intelligence could even be increased by the virus. However, before the testing could begin in full, soldiers under the command of Roger Maxson rebelled and executed the science staff. With the Great War destroying the United States, Mariposa and research within was sealed by the soldiers and abandoned.[85]


Vault 87[]

Modified FEV was utilized as a part of the Vault 87 experiment. The scientists within the Vault noted their efforts toward the Evolutionary Experimentation Program, or EEP, at the behest of Vault-Tec and the military members at Mariposa.[86] Some strains caused fatalities, and causes of death were obscured from family members. A year, the test subjects broke free and overran the Vault, using its FEV reserves to transforms all humans they could find. Since then, they became a permanent feature of the Capital Wasteland, preying on human communities and abducting them,[87] consumed by an overpowering urge to increase their numbers. Although almost universally brain damaged and comparable to later second generation Mariposa mutants, the EEP sometimes functioned correctly and created intelligent mutants. These unique individuals, like Uncle Leo or Fawkes, possessed a very high level of intelligence on top of their imposing physical features.[88]

Occasionally, the EEP created a smart super mutant who wasn't immediately scorned by their dumb brethren, allowing these individuals to rise to prominence as vicious warlords. Shepherd was one such notable mutant, attempting to reorganize the Capital Wasteland super mutants into a horde around 2282, and was stopped by Brotherhood forces under Elder Arthur Maxson.[89] However, owing to two centuries of proliferation and FEV's effects, super mutant hives became commonplace, with stockpiles of FEV retrieved from biomedical facilities in the East used to force the irreversible transformation on any human subject the mutants could capture.[90]

The Unity[]

The vats were rediscovered in 2102 by an expedition led by Harold, a major Hub merchant. Accompanied by Richard Grey, a brilliant exile from Vault City, he managed to crack the Mariposa base security and infiltrate the lower levels. However, within the vats, the automated crane crashed into the two, knocking Harold out and flinging Grey into the vat with FEV. Harold woke up in the wastes outside the base, mutating due to exposure to FEV fumes, but becoming a special type of a ghoul-like mutant, rather than a super mutant. Grey, on the other hand, underwent extreme mutation due to prolonged exposure to the virus in the vat. His intellect grew exponentially, allowing him to comprehend even the most complex issues easily (or so he thought).[Non-game 8][91] Grey methodically researched FEV, experimenting with animals and eventually, captured scavengers that strayed into the facility. It was not until a few failed mutations that he discovered radiation count to be a deciding factor in the success of the change, leading him to pick subjects more carefully.[91][Non-game 9] When his Lieutenant was created, he suggested a secondary reason for possible incompatibility. Reviewing available evidence, he concluded that failed mutations in relatively non-radiated humans are caused by the inoculating effect mutated FEV had on humans with which it came into contact.[12] Such exposure was not enough to cause phenotypical changes, but enough to cause conflicts when the pure FEV in Mariposa attempted to change the DNA, resulting in the death of the subject.[92]

By carefully selecting his test subjects, he managed to create the first real super mutants in January 2103.[Non-game 10] Through a combination of willing converts and abductions, the Master slowly builds up the foundations for his army between 2103 and 2130.[Non-game 11] The impact of the Great Winter of 2130 results in him stepping up his operations and spreading them out into the wasteland, attacking caravans to gather human stock for transformations. The string of attacks between 2131 and 2135 boosts the size of his army. The attacks are blamed on desert monsters in the Hub.[Non-game 12] Due to reliance on wastelanders, only 20% of the dipped population survives the dipping and of that number, only half seem to last and become a part of the Unity. Regardless, it continues to grow.[Non-game 13]

By 2152, the Unity's influence has spread through the wastes and the Master recruited a group of doomsday cultists under Morpheus to act as spies, rather than stock for transformation.[Non-game 14] Four years later, the cultists would form the Children of the Cathedral to act as a front for the Unity, proselytizing, recruiting, and preparing munition dumps for the coming super mutant offensive.[Non-game 15] Between 2155 and 2156, the Master makes another important discovery: His forces intercept a caravan of Vault dwellers, leading him to discover Vault-Tec's demonstration Vault. He moved his command center to the Vault, using the cultists to set up the Cathedral, and launched a campaign to discover Vaults to gain prime subjects for his super mutant army.[Non-game 16] At least one installation, Vault 17, was discovered and its inhabitants transformed into super mutants. The success rate is far higher than when using regular wastelanders. Even the elderly Lily Bowen was successfully transformed into a super mutant at the age of 75 - and a nightkin no less![93]

The Master and his staff also experimented with FEV by injecting it into the brains of the subjects (usually the pineal gland, but also the amygdala or medulla), triggering changes in brain chemistry.[44] These experiments had limited success: four extremely powerful psykers were created, capable of theoretically wiping out the human race.[Non-game 4]

By 2161, the Unity was on the verge of achieving total military superiority over the human inhabitants of New California. All that was needed was Vault 13 and its inhabitants.[94] All FEV development and experimentation by the Master was abruptly halted by the Vault Dweller, of the very Vault the Master needed to dominate the New West.[95]

Vault 96[]

Edgar Blackburn began his own, independent research initiative into FEV, after realizing that observation, not a cure, was the purpose of the West Tek initiatives at Huntersville.[96] He was not sure what the purpose of infecting the water supply was, apart from this observation, as they knew the virus in its current state "produced horrors."[96][97] He resolved to make good on the promise of FEV and create a true immunizing agent that would cause humanity to evolve. Blackburn continued his work after the war in Vault 96, utilizing human subjects abducted by a group of mercenaries called the Hellcat Company in an attempt to create "perfected FEV."[98][99] Super mutants created were considered failures by Blackburn, and set free outside the Vault.[100] Ultimately, Blackburn and his work were ended by the intervention of the Brotherhood First Expeditionary Force and a Vault Dweller from Vault 76.[101]

Enclave FEV Curling-13[]

Seeking the means to achieve their plans of global genocide, the Enclave excavated Mariposa from July to August 2236, in search of surviving samples of FEV-2. Using slaves captured in towns across New California, they managed to uncover the vats and secure the necessary scientific material. However, slaves exposed to the raw virus in the ruins of the base mutated, creating the second generation super mutants.[12] The uneven nature of exposure, coupled with a significant radiation count meant that those that survived the change suffered from significant mental damage. Retreating from the base, the Enclave blasted the only remaining entrance, trapping the mutants inside.[12]

The Enclave's Chemical Corps proceeded to work on the acquired samples of the virus, creating a staggeringly effective killer, tailored to provide maximum lethality with minimal required exposure. However, two weeks before the virus' deployment, the Enclave, and the virus stockpiles were destroyed. However, copies of research were transmitted to Raven Rock, providing Raven Rock's ZAX John Henry Eden with an opportunity to achieve plans of genocide. After modifying the FEV Curling-13 to only target the heavily mutated and heavily irradiated, the ZAX unit decided a localized infection of the water supply would be more effective at culling the undesirables while also improving the quality of life for the unmutated and unirradiated.[102][103][104]

Enclave modified FEV[]

The Enclave contingent in the Capital Wasteland utilized a modification of FEV at the behest of President John Henry Eden.[62] This modified FEV was created in an attempt to murder individuals living in the area by contaminating the water supply using the Project Purity facility.[102] President Eden states that the only people who would survive the infection are members of the Enclave and those who were born in the Vaults.[64][103] These plans ended with the destruction of Raven Rock and the Brotherhood of Steel's reclamation of Project Purity, and by 2287 the region is known to have purified, drinkable water.[105]

The modified FEV specifically targets the immune system of infected individuals on a cellular level.[65][66] Barrows mentions that ghouls are usually immune to diseases, but are impacted alongside humans.[66] The modified FEV is undetectable in water that has been infected.[68][69]

The Institute[]

Commonwealth super mutants are the result of the Institute's research into FEV, which has continued since the early 2220s in a dedicated facility. The original goal was the creation of a successor to second generation synths by creating a new breed of super mutant that would serve the Institute as laborer and soldier. Due to a lack of success with mutants, efforts were refocused with the goal of creating third-generation synths. The organic synth project was spun off from the FEV research initiative around 2227 (the acquisition of Shaun), while the FEV research effort continued for several more decades.[50][51] Both women and men were abducted from the Commonwealth and submerged in the Institute's modified FEV, their mutations carefully tracked. Successful mutations were monitored to ensure survivability, then tagged and discarded.[106] In layman's terms, the Institute was simply releasing super mutants into the wild, creating a scourge on the Commonwealth that lasted for years.[107] When Brian Virgil succeeded Dr. Syverson as head of the project in April 2286, it became evident that FEV experimentation ran its course and served no useful purpose, not with the availability of third generation synths.[52] Eventually, as Virgil's conscience took its toll, the scientist lodged a formal complaint with the Directorate.[50] When no reaction came, Virgil rebelled and escaped the Institute after transforming himself into a super mutant, destroying as much of the project as he could.[108] The wrecked FEV lab was marked as a biohazard area and sealed off in the wake of his escape.[109][110] The whole incident was covered up, even from ranking Institute members such as Madison Li, contributing to her dissatisfaction.[111]


The Forced Evolutionary Virus appears in Fallout 2, Fallout 3, Fallout 4 and Fallout 76. It is also mentioned in Fallout: New Vegas.

Behind the scenes[]

[A] dip in FEV has a chance of modifying Intelligence, but it doesn't always increase it. Some people do gain increased intelligence, a larger majority lose intelligence and most people remain the same. It also depends if people have enough radiation damage to be turned into ghouls or super mutants.Chris Taylor, Fallout Bible 5
Why did we bother with the Forced-Evolutionary Virus and not just say radiation caused the mutations? Unfortunately, science tells us high levels of radiation just kill things. Lower levels can cause mutations, but more than 99% aren’t advantageous, and often lead to early death. I wanted to explain how something like a Radscorpion could have evolved and proliferated in the course of 60 years – and to me, “it’s the power of radiation!” was way-too-obvious junk science. Because I wanted a plausible game back-story, I wanted explanations that were a little more scientifically plausible (or at least more believable than the plot to THEM!) I also wanted this virus to be part of the main villain’s master plan – making a race of super mutants from human stock by subjecting them to a vat of this refined viral agent.Scott Campbell, The Origins of Fallout
  • Scott Campbell further elaborated on the idea in Origins, noting that the idea was to suggest that FEV was one of the catalysts for the Great War and an explanation for The Glow being a giant, gaping crater.[Non-game 17]
  • The Fallout FEV variant is usually referred to as just FEV, sometimes distinguished with an appendix, identifying it as FEV-2. Games consistently use Arabic numerals. Roman numerals, FEV-II, are used only in the Fallout Bible.
  • FEV-2 is a remnant of the early designs, where there was a distinct FEV-1 worked on at what would eventually become the Glow. FEV-1 was created in 2057 and eventually gave way to FEV-2, the superior virus that would create the super mutants. This distinction is not explicitly noted in the game, where the FEV's forerunner is identified as the Pan-Immunity Virion. Both are consistently answers to the New Plague, however.
    • To elaborate, FEV was originally designated just FEV, when it was still a variant of the PV. It was subsequently heavily modified and altered, with each modified batch used for testing on ever more complex organisms. However, the term FEV-2 is used at several points in the game (eg. by Dane) to refer to the FEV strain in Mariposa, and is later explicitly used in the Fallout: Brotherhood of Steel manual to identify a superior version of the virus.[112] In most cases, the FEV-2 variant is simply referred to as just FEV, with an explicit mention of FEV-1 not found.
    • One potential method to identify the variants is by using batches. FEV was originally a variant of PV, using batch 10-011 (corresponding to 2-3 in decimal; the identifier 01 or 1 in decimal could signify PV), provisionally named FEV in March 2075. The version that would become FEV-2 is identified as 11-111 (3-7), the result of combining batches 11-011 (3-3) and 11-101a (3-5a) from January and May 2076, respectively.[32]



FEV subjects[]




  1. The Vault Dweller: "{215}{}{And how do we achieve this perfect Utopia? }"
    Slummer: "{287}{}{We must submit to the Master and the Holy Flame. When we have proven ourselves, we shall become baptized and closer to God. When all have been baptized, we shall be as one, a Unity under the Master! }"
    The Vault Dweller: "{288}{}{Tell me more about this baptism. }"
    Slummer: "{328}{}{The baptism will change us all, and bring our physical forms closer to God's own image. When we have all become God, all our differences will disappear, so we can have peace and unity at last, and there will never be war or destruction again! }"
    The Vault Dweller: "{231}{}{That sounds like he's going to dump everybody in the FEV-2 Virus! }"
    Slummer: "{322}{}{Of course he won't. He's the Master. He would never do that to his disciples. It is his holy power through baptism, and the Holy Flame, that will transform us. The virus is an evil of the old time, which I'm sure will be cleansed. }"
  2. 2.0 2.1 2.2 The Vault Dweller: "{133}{}{I happen to know that your mutants are sterile.}"
    Master: "{135}{Mast11}{Preposterous! The FEV-2 virus doesn't destroy the reproductive organs of those it mutates.}"
    (Master's dialogue)
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Vree's autopsy report
  4. The Sole Survivor: "How did mankind abuse technology?"
    Danse: "Before the Great War, science and technology became more of a burden than a benefit. The atom bomb, bio-engineered plagues and FEV are clear examples of the horrors that technological advancement had wrought. We're here to make sure that never happens again."
    (Danse's dialogue)
  5. 5.0 5.1 The Vault Dweller: "{164}{}{Why isn't FEV affected by radiation?}"
    ZAX 1.2: "{166}{}{The FEV is a megavirus, with a protein sheath reinforced by ionized hydrogen. It is therefore capable of absorbing neutrons without becoming radioactive.}"
    (ZAX 1.2's dialogue)
  6. 6.0 6.1 The Vault Dweller: "{159}{}{How do you catch FEV?}"
    ZAX 1.2: "{162}{}{FEV is not 'caught', per se. It is not air-transmittable. Typically, infection is through injection, or direct physical contact with an FEV sample.}"
    (ZAX 1.2's dialogue)
  7. Mariposa Military Base#Structure
    West Tek research center (Fallout 76)#Layout
  8. 8.0 8.1 The Project: "Final tests conducted on the vault-descendant subjects, from the village "Arroyo," have shown a survival rate of zero-percent, with most deaths occurring within one-hour of exposure to a .0001% aerosol solution. By contrast, the subjects extracted from Vault 13 tend to suffer subdural hemorrhaging and convulsions within one-hour of exposure, with death not occurring, on average, for another 14.5-hours."
  9. The Vault Dweller: "{120}{}{How does the Virus work?}"
    ZAX 1.2: "{157}{}{My research into the Forced Evolution Virus, or FEV, indicates that it is a shifting-absorptive virus. It copies DNA patterns much like RNA, storing these patterns in exons.}"
    "{158}{}{These exons, combined with the FEV, are re-injected into the host cells in typical viral infectious fashion. This causes the host cells to 'regenerate' their DNA.}"
    (ZAX 1.2's dialogue)
  10. 10.0 10.1 10.2 The Vault Dweller: "{168}{}{If the FEV re-infects the host with its assimilated viral patterns, how does it make a 'better specimen'?}"
    ZAX 1.2: "{169}{}{The FEV is pre-programmed with introns of corrected DNA appropriate to the proper type of species. It therefore attempts to correct the DNA of the individual.}"
    "{170}{}{However, as the FEV is partially reliant upon the DNA of the individual, and also includes portions of its own recursive code, the effects can be unpredictable.}"
    "{171}{}{When inoculated into an individual with significant genetic damage, such as through radiation, it will cause the body's systems to suffer massive overhauling, leading to organ failure and death.}"
    "{172}{}{In a genetically viable individual, it re-writes portions of DNA, causing accelerated mutation, usually leading to recursive growth due to the FEV's own patterns.}"
    "{173}{}{This recursive growth leads to an increase in muscle and brain mass, but is often accompanied by disfigurement and damage to existing neural patterns, causing loss of memory.}"
    (ZAX 1.2's dialogue)
  11. Dipping cutscene
  12. 12.0 12.1 12.2 12.3 12.4 Military base level 4
  13. 13.0 13.1 The Vault Dweller: "{109}{}{I want to know what's happening with your experiments.}"
    Mad scientist: "{112}{}{It's not going well. I've been injecting the FEV directly into the pineal gland, but I'm not getting the results I'd hoped for.}"
    The Vault Dweller: "{115}{}{What results are you getting?}"
    Mad scientist: "{120}{}{The Master's truth is revealed, resulting in increased psychic ability. [shakes his head] But the poor souls become terminally insane and must be sequestered and nullified to keep them from harming themselves or others.}"
  14. The Vault Dweller: "{109}{}{I want to know what's happening with your experiments.}"
    Mad scientist: "{112}{}{It's not going well. I've been injecting the FEV directly into the pineal gland, but I'm not getting the results I'd hoped for.}"
    The Vault Dweller: "{116}{}{Hmmm. And?}"
    Mad scientist: "{150}{}{[shakes his head] Alas, the poor souls become terminally insane and must be sequestered and nullified to keep them from harming themselves or others.}"
    The Vault Dweller: "{151}{}{Oh, how thoughtful of you...}"
  15. Richard Grey's audio diary; 0000 - 0004, 0021 - 0027, 0028 - 0043, 0044 - 0057
  16. 16.0 16.1 The Lone Wanderer: "So, tell me more about yourself."
    Fawkes: "I was born here, in this place. I don't mean that in the literal sense of course. All I can remember is the excruciating pain that tore through me as my body underwent the rapid physical changes. For most, this moment is what severs the grip on their minds. They become barely a shell of their former selves. I was different. When I spoke to them, they immediately branded me "another failure" and had me placed here as a curiosity."
    (Fawkes' dialogue)
  17. 17.0 17.1 The Vault Dweller: "{188}{}{Why am I a prime human ?}"
    Lieutenant: "{194}{LIEUT30}{The FEV was mutated by the war radiation. Those living in this desolate wasteland have been exposed to this mutant FEV, essentially inoculating them from the full effects.}"
    The Vault Dweller: "{195}{}{So?}"
    Lieutenant: "{197}{LIEUT31}{So, you're from a Vault and have limited exposure to this mutated virus. The original FEV in the Vats should work quite well on you.}"
    The Vault Dweller: "{198}{}{And how do you know this?}"
    Lieutenant: "{199}{LIEUT32}{We have done extensive experiments on humans to reach this conclusion. My master has been searching for unopened Vaults to prove his theories. And now you've come along. How thoughtful of you.}"
  18. 18.0 18.1 18.2 The Chosen One: "{201}{}{Okay, now I know where you found it, but what does it do?}"
    Charles Curling: "{202}{}{The F.E.V. was initially designed as a virus that was supposed to turn humans into super-soldiers. That experiment seems to have been an utter failure, although I did try a modification of the virus on one of our Secret Service agents with some success.}"
    The Chosen One: "{203}{}{Great for you, but how does that have anything to do with eradicating everyone?}"
    Charles Curling: "{204}{}{Oh, yes, well, I was getting to that….The F.E.V. virus bond is species specific, it will only bond with human glyco-proteins. It only took a few years to tweak the F.E.V. virus to make it more lethal than it all ready was. The result was just what the doctor ordered, perfect in every way. }"
    The Chosen One: "{205}{}{Perfect? How so?}"
    Charles Curling: "{206}{}{Isn't it obvious, my mutated friend? The F.E.V. is, thanks to me, a lethal toxin, and thanks to some mysterious genius named, rather dramatically, the Master, it only works on humans, mutated or not.}"
    The Chosen One: "{207}{}{So?}"
    Charles Curling: "{208}{}{That means that we have the perfect disposal device for all of the near-human mutants infecting the globe. }"
    The Chosen One: "{209}{}{I still don't understand how that's *perfect.*}"
    Charles Curling: "{211}{}{The F.E.V. toxin will only attack to humans, leaving everything else alive, better still, within a month all the mutants will be dead and the F.E.V. toxin will die out as soon as it runs out of hosts. }"
  19. The Lone Wanderer: "What's the goal of your experiments?"
    Weston Lesko: "By introducing my mutagen directly into an ant egg, I hope to reduce the size of the adults. This is a generational system, meaning it will take quite a few broods before the ants are at their destination size. In the end, I hope to make them as small as they were over 200 years ago."
    (Weston Lesko's dialogue)
  20. The Lone Wanderer: "Something isn't right. You shouldn't have gotten results like these so quickly."
    Weston Lesko: "Well... ummm, I may have used a few... ahem, shortcuts. Yes. I was told that the FEV works wonders when used under controlled circumstances! Apparently I was wrong, but I know my mistake. I'm certain I can get it to work!"
    (Weston Lesko's dialogue)
  21. The Chosen One: "{138}{}{Maybe it's all that extra radiation.}"
    Master: "{171}{Mast28}{Radiation has no effect on us. The FEV virus makes us immune. Your argument is weak, and so are you.}"
    (Master's dialogue)
  22. The Vault Dweller: "{141}{}{How are you more advanced?}"
    Lieutenant: "{149}{LIEUT14}{Intuitively obvious to the most casual observer. We are highly intelligent and immune to disease. The strong survive! It is our goal to improve the human race.}"
    (Lieutenant's dialogue)
  23. 23.0 23.1 The Vault Dweller: "{174}{}{What potential long-term side effects exist?}"
    ZAX 1.2: "{178}{}{As the FEV causes constant regenerative update to DNA, it would effectively render the subject largely immortal, as cell death would be offset by augmented growth.}"
    "{179}{}{Additionally, as the gametes of the reproductive system consist of 'half-cells' using split DNA, they could be perceived as 'damage' by FEV, which would 'repair' them, rendering the subject sterile.}"
    "{180}{}{However, as my laboratory facilities are damaged beyond repair, this is conjectural. I cannot offer physical proof. You will have to, in human terms, 'take my word for it.'}"
    (ZAX 1.2's dialogue)
  24. The Chosen One: "{349}{}{Uh... when you said 'I hope she doesn't get pregnant' in the Cat's Paw in New Reno, what did you mean?}"
    Marcus: "{350}{mcs113}{Didn't your parents explain this to you?}"
    The Chosen One: "{351}{}{No, I mean, I thought all you mutants were sterile.}"
    Marcus: "{353}{mcs114}{What? Where the hell did you hear that?}"
    The Chosen One: "{354}{}{So... you AREN'T sterile?}"
    Marcus: "{356}{mcs116}{Nope. Well, not now. It takes a few years after bein' dipped to get the juices flowing again. Why?}"
    The Chosen One: "{357}{}{Oh. Uh. Never mind.}"
  25. The Vault Dweller: "{156}{}{Did you think to ask a female mutant?}"
    Master: "{162}{Mast25}{Reasonable. One moment. Are you sure? What about the other females? It cannot be. Be.}"
    The Vault Dweller: "{163}{}{Sorry, your race is doomed.}"
    Master: "{149}{Mast17}{But it cannot be. This would mean that all my work has been for nothing. Everything that I have tried to . . . a failure! It can't be. Be. Be. Be.}"
    The Vault Dweller: "{150}{}{Sorry, this isn't an option for you. Your race will die out after this generation.}"
    Master: "{153}{Mast19}{I . . . don't think that I can continue. Continue? To have done the things I have done in the name of progress and healing. It was madness. I can see that now. Madness. Madness? There is no hope. Leave now, leave while you still have hope . . .}"
  26. The Vault Dweller: "{181}{}{Could FEV mutation be corrected with a counter-virus?}"
    ZAX 1.2: "{184}{}{No. FEV does not retain unaltered original copies of the subject's DNA. Only a virus which re-infected the subject with original DNA could reverse the effects. Additionally, there is no known way to remove the FEV itself.}"
    (ZAX 1.2's dialogue)
  27. 27.0 27.1 The Chosen One: "{237}{}{What about my people? Or me? Or you, for that matter?}"
    Charles Curling: "{238}{}{I can release the antidote into the air-system for all the cells. The detention level is served by a separate air system from the rest of the Enclave. Everyone will think that I'm just running another test. You, I can inoculate directly, here and now. (he reaches for you with a syringe)}"
  28. The Sole Survivor: "It'll work. Don't worry."
    Brian Virgil: "I hope so. We just have to let the retrovirus run its course. I'm going to rest for a while. Come back in a few days, maybe a week, and... well, I guess we'll see. In any event, you kept your end of our bargain. Thank you."
    (Brian Virgil's dialogue)
  29. Brian Virgil: "All right. Let's see, let's see... Retrovirus has matured nicely. Density gradient is high... Recombinant counter-intron sequences look stable... Transcriptive exon strands have formed..."
    (Brian Virgil's dialogue)
  30. Brian Virgil: Welcome back. It needs some refinement, but I think we can consider my serum a qualified success."
    The Sole Survivor:
    "This is a "qualified success"?"
    Brian Virgil:
    "There were some side effects to the process. I seem to have hair again. And I've retained some muscle mass. The genetic resequencer needs more work. Still, I take your point. This is a significant advance. But only for one strain of FEV. It will take years, perhaps decades, to generalize my formula. Still, you have my gratitude."
    (Brian Virgil's dialogue)
  31. ZAX:"{118}{}{Research into possible cures for the New Plague created the Forced Evolutionary Virus, which was further developed in an attempt to create a transmittable genetic-engineering virus -- in effect, infectious evolution.}"
  32. 32.00 32.01 32.02 32.03 32.04 32.05 32.06 32.07 32.08 32.09 32.10 32.11 32.12 32.13 32.14 FEV experiment disk
  33. FEV research
  34. Charles Curling: "{202}{}{The F.E.V. was initially designed as a virus that was supposed to turn humans into super-soldiers. That experiment seems to have been an utter failure, although I did try a modification of the virus on one of our Secret Service agents with some success.}"
  35. 35.0 35.1 Dane: "{181}{}{I'm screwed, but this is only Phase 1 of the Cathedral Screwover Plan. When servitors get completely brainwashed, they got to Phase 2. That's when the Master baptizes them in the FEV-2!}
    {182}{}{Most die right there. But those who survive become mutants. BIG mutants. Nightkin! The Master thinks that only the Nightkin can survive. He wants to make everyone Nightkin because they're tough!}"
  36. Richard Grey's audio diary; 0173 - 0198, 0199 - 0236
  37. The Vault Dweller: "{142}{}{What is the current status of the patients?}"
    Vats control computer: "{143}{}{Current status on patients as follows: FEV batch #23872-A consists of four male units and two female units. All individuals suffering from FEV exposure. Vital signs are within normal parameters. FEV process on all subjects is approxiamtely 50% complete. Expect full FEV transformation within 12 hours.}"
    (Vats control computer dialogue)
  38. The Chosen One: "{358}{}{Of course, Captain. Let me see what I can do for you and your friend.}"
    Troy: "{361}{}{My, your mutant friend had a great deal of bullets and shrapnel lodged in his body. It's a wonder he didn't have lead poisoning. I finally managed to get it all out. Here it all is.}"
    (Troy's dialogue)
  39. The cybernetic implants, self-mutilation scars, and the amputated tongue of the Lieutenant, Dog and God, and Mean Sonofabitch respectively are examples of permanent tissue damage.
  40. Marcus's facial growth.
  41. This is reflected in the pre-placed populations at Mariposa, Cathedral, and Necropolis. There's a total of 73 pre-placed characters (including generic and named mutants), totaling 27 "grunts" (unarmored super mutants, signifying cannon fodder), and 44 Nightkin (as in, proper super mutants, distinguished by their black gear, Harry is the sole exception), plus one Lieutenant. All of the grunts have low intelligence and together with Harry make up 38% of the population (the larger majority), while the Nightkin (18 officers at Mariposa and 28 at the Cathedral and the Master's Lair) represent 60%. The super-intelligent outlier, the Lieutenant, is about 2%.
  42. Black Mountain Radio; Know Your Mutants; segment three
  43. The Courier: "How did Tabitha end up in control?"
    Neil: "For years, Black Mountain was a peaceful community. Its leader, Marcus, broadcast an invitation to Mutants throughout the wasteland. That's how I found Black Mountain. So did others, most of them second generation Mutants. Marcus welcomed everyone - that was his mistake. The community ended up being mostly second gen - not very bright, but easy to influence. Fine, until the Nightkin came along, led by Tabitha... In a week she had most of the second-gens thinking she was some kind of prophet - and that she should be broadcasting her "truth," not Marcus. Marcus saw what was coming and decided to leave before things got out of hand. He smashed the radio and left to found Jacobstown."
    (Neil's dialogue)
  44. 44.0 44.1 Mad scientist: "{101}{}{Good evening, brother. What brings you to our little corner of heaven?}"
    The Vault Dweller: "{103}{}{I'm here to check on your progress.}"
    Mad scientist: "{112}{}{It's not going well. I've been injecting the FEV directly into the pineal gland, but I'm not getting the results I'd hoped for.}"
    The Vault Dweller: "{113}{}{Why don't you try injecting it directly into the Amygdala?}"
    The Vault Dweller: "{114}{}{Why don't you try injecting it into the Medula?}"
    Mad scientist: "{129}{}{What an intriguing idea! I must try it at once!}"
    (Mad scientist's dialogue)
  45. 45.0 45.1 45.2 Vault 87 terminal entries; Chief Physician's Terminal
  46. The Lone Wanderer: "Do you remember who you were?"
    Fawkes: "I don't remember enough to tell you everything about my former self. My metamorphosis destroyed a good deal of my long term memory. However, I can recall being in this place when it wasn't the macabre laboratory that it's become. I remember walking around this place and seeing other humans in white lab coats and blue jumpsuits. I wish I could find out more, but the personnel information for the Vault wasn't in the mainframe for some reason. I feel like my identity is so close to me... I can almost see myself as a human but can't recollect the details. It's maddening."
    (Fawkes' dialogue)
  47. The Prydwen terminal entries; Scribe Neriah's Terminal, Entry 0769-CM22
  48. Fallout 4 loading screens: "Super Mutants are stronger and more resilient than humans, and consider themselves the Commonwealth's superior race."
  49. The Sole Survivor: "Human synths? Really?"
    Shaun: "Human-like synths. A great distinction. The Institute endeavored to create synthetic organics. The most logical starting point, of course, was human DNA. Plenty of that was available, of course, but it had all become corrupted. In this... wasteland... radiation affected everyone. Even in their attempts to shield themselves from the world above, members of the Institute had been exposed. Another source was necessary. But then the Institute found me, after discovering records from Vault 111. An infant, frozen in time, protected from the radiation-induced mutations that had crept into every other human cell in the Commonwealth. I was exactly what they needed. And so it was my DNA that became the basis of the synthetic organics used to create every human-like synth you see today. I am their Father. Through Science, we are family. The synths, me... and you."
    (Shaun's dialogue)
  50. 50.0 50.1 50.2 FEV lab terminal entries; terminal, 2287.2.10: "Entered By: Virgil.B
    Nothing new. Always the same. Have entered formal complaint with Directorate; these tests are not bringing in any valuable information. The organics project was spun off decades ago. Why do we insist on continuing this?"
  51. 51.0 51.1 FEV lab terminal entries; terminal, 2277.7.10: "Entered By: Syverson.C
    Latest round of testing complete. Results are all within expected parameters. Informed Dr. Zimmer directly, as he had ordered the tests personally. He seemed annoyed with the results; unsure what he was looking for. He declined to specify why he wanted the tests run to begin with."
  52. 52.0 52.1 FEV lab terminal entries; terminal, 2286.4.10: "Entered by: Virgil.B
    I have officially assumed the lead role on the project after Dr. Syverson's passing.
    Latest round of subjects show results similar to previous test runs over last 5 years. No statistical deviation noted."
    Synthetic organics continue to perform well; the necessity of further tests is unexplained."
  53. The Sole Survivor: "How do they make synths?"
    Glory: "Damned if I know. The machines are... massive. Complicated. Not like anything I've seen out here. No matter what Dez and others say, synths ain't human. We're assembled bone by bone. Muscle by muscle. I've seen it. I'm gonna hit the range. I need to shoot something. Now."
    (Glory's dialogue)
  54. The Sole Survivor: "What makes them superior?"
    Max Loken: "The list of improvements is exhaustive. I can talk for an hour and still not cover all of it. Imagine what you could accomplish if you could live without fear of hunger or disease. Imagine what you could create if you could use every waking moment of your life as you saw fit, with no need of sleep? Like I said, a momentous time."
    (Max Loken's dialogue)
  55. Institute Robotics terminal entries; Robotics terminal, Upcoming projects
  56. Fallout 76 loading screens: "The first Super Mutants in Appalachia were created right before the Great War, when West Tek poisoned the drinking water of Huntersville with the FEV Virus, in a sinister, secret experiment gone horribly wrong."
  57. 57.0 57.1 West Tek research center terminals; Advanced mutations lab terminal, Report: Test Subject AM52
  58. West Tek research center terminal entries; Advanced mutations lab terminal, SPECIAL REPORT: CONTAINMENT BREACH
  59. 59.0 59.1 West Tek research center terminals; Advanced mutations lab terminal, Report: Test Subject AM53
  60. The Brain: " {150}{}{Are you ready to become one of us?}"
    The Chosen One: "{152}{}{You mean become a giant rat?}"
    Brain: "{360}{}{You humans have such limited tolerances. I would have remained a normal rat if you humans hadn’t done your best to destroy the world. If it weren’t for the radiation, I wouldn’t be what I am today.}"
    The Chosen One: "{361}{}{And what’s that, exactly?}"
    Brain: "{380}{}{I was just one of many normal rats in a advanced research lab. Then, one day, there were explosions. Our cages were broken open, and we were doused with some sort of fluid from a huge vat.}"
    The Chosen One: "{381}{}{Then what?}"
    The Brain: "{390}{}{I crawled outside. As I began to heal, I noticed that I had changed. I tried to communicate with people, but they all just tried to kill me. Humans are just too violent to survive under their own leadership -- but that's another story. The first step is to repair the reactor.}"
    (The Brain's dialogue)
  61. Dick Richardson: "{199}{prs26}{Vice-President Bird may look like a drooling idiot, but I'll have you know that man's a national hero.}"
    The Chosen One: "{200}{}{To you, probably.}"
    Dick Richardson: "{201}{prs27}{He's one of the bravest men I know. He volunteered to try one of the early versions of the F.E.V. toxin antidote. (sigh) Unfortunately, it didn't quite work out the way we'd hoped.}"
    The Chosen One: "{202}{}{You mean that wasn't what you'd hoped for?}"
    Dick Richardson: "{203}{prs28}{It's tiny mocking minds like yours that prove the superiority of real humans over mutants.}"
    The Chosen One: "{204}{}{He's still a gibbering idiot.}"
    Dick Richardson: "{206}{prs29}{He may yet come around. In fact, there may even be some unforeseen benefits. His spelling ability has actually improved.}"
    The Chosen One: "{207}{}{I'm happy for you. But why did you call me a mutant?}"
  62. 62.0 62.1 The Lone Wanderer: "Where did this plan of yours come from?"
    John Henry Eden: "A great many years ago, the remnants of the government had a similar idea. I can only assume the plan failed, as I never heard word of its success. But the plan itself was sound. I've made a few modifications, and with your help, I do believe it can work. There's a bright future ahead of us, my young friend."
    (John Henry Eden's dialogue)
  63. The Lone Wanderer: "Say whatever it is you have to say."
    John Henry Eden: "Our land is ravaged by mutation. The war was so many years ago, and yet we still suffer from its effects. We cannot move forward until humanity can gain a solid foothold in the world. To do so, we must rid ourselves of the mutations that have plagued us for so long. These "Super Mutants", Ghouls, hideous creatures... I believe your father's work can do that in a way unlike any other."
    (John Henry Eden's dialogue)
  64. 64.0 64.1 The Lone Wanderer: "Won't this kill pretty much everyone in the Wasteland?"
    John Henry Eden: "Anyone or anything that has been affected by mutation will be eliminated. You will likely be immune, thanks to your upbringing in the Vault. Likewise, the good people of the Enclave will be unaffected as well. I understand that you may have become sympathetic to certain individuals in your travels. Individuals this will eliminate. Please recognize that the fate of our entire country rests on this plan. Sacrifices must be made for the greater good."
    (John Henry Eden's dialogue)
  65. 65.0 65.1 65.2 The Lone Wanderer: "Doc, it's crowded in your clinic. Something going around I should worry about?"
    Preston: "Oh no... I'm fairly certain it's not contagious. Though, we are burning the bodies of the deceased, just in case... I just wish I knew how to treat these people. It's like their immune system is killing them. I don't know what to do about it!"
    (Preston's dialogue) Note: This is the response given should the player have completed the quest Project Impurity by infecting the water supply with modified FEV.
  66. 66.0 66.1 66.2 The Lone Wanderer: "Full house today, Doc. What's wrong with everybody?"
    Barrows: "I don't know yet. Some kind of virus that attacks the body on a cellular level. I've never seen anything like it. It's strange, because Ghouls are immune to almost any known disease."
    (Barrows' dialogue) Note: This is the response given should the player have completed the quest Project Impurity by infecting the water supply with modified FEV.
  67. If the Lone Wanderer drinks four bottles of Aqua Pura infected with the modified FEV, they suffer increasingly negative effects (that are temporary) such as loss of Strength and Intelligence until the last bottle that kills them.
  68. 68.0 68.1 The Lone Wanderer: "Something going around, Doc? The clinic seems pretty full today."
    Church: "There's something going around, all right, but it isn't anything I've ever seen before. Definitely not contagious. Maybe something in the water, but that seems unlikely since I've tested it and this is the cleanest water we've ever had. Be damned ironic if we were so used to the crap we've been drinking that actual pure water was killing us."
    (Church's dialogue) Note: This is the response given should the player have completed the quest Project Impurity by infecting the water supply with modified FEV.
  69. 69.0 69.1 The Lone Wanderer: "What's with all the patients? You seem busier than usual."
    Church: "I have no idea how to help these people and it's really taken the shine off my normally sunny disposition. So unless you have an actual medical problem, maybe you could stop distracting me from my work."
    (Church's dialogue) Note: This is the response given should the player have completed the quest Project Impurity by infecting the water supply with modified FEV.
  70. Intelligent deathclaws in Fallout 2.
  71. Canon Fallout 2 endings
  72. The Lone Wanderer: "So, what's gone wrong?"
    Weston Lesko: "Well. I'm afraid I've made slight miscalculations in the mutagen. Instead of lowering their size, the brood hatched with a new biomechanism. I call their genetic abberation pyrosis; the ability to emit flame from their bodies. I may be able to correct this error, but I can't get near my equipment."
    (Weston Lesko's dialogue)
  73. Marigold station terminal entries; Doctor Lesko's terminal
  74. Grayditch terminal entries; Doctor Lesko's terminal
  75. 75.0 75.1 FEV research
  76. West Tek research center terminals; Greenhouse control terminal, Greenhouse Initiative
  77. Huntersville terminals; Gail Meyer's terminal, Personal Journal 08.20.75
  78. Huntersville terminals; Gail Meyer's terminal, Personal Journal 12.20.75
  80. West Tek research center terminals; Analysis terminal, FTS-3A Water Analysis
  81. West Tek research center terminal entries; Advanced mutations lab terminal, Report: Test Subject AM48
  82. West Tek research center terminal entries; Advanced mutations lab terminal, Report: Test Subject AM49
  83. West Tek research center terminal entries; Advanced mutations lab terminal, Report: Test Subject AM50
  84. West Tek research center terminal entries; Advanced mutations lab terminal, Report: Test Subject AM51
  85. History of the Brotherhood of Steel
  86. Vault 87 terminal entries; Chief physician's terminal, Entry 87-34190
  87. Vault 87 terminal entries; Engineering section, Service Issue Entry V87-007
  88. Uncle Leo and Fawkes
  89. The Prydwen terminal entries; Proctor Quinlan's terminal, The Rise of Elder Maxson
  90. The Sole Survivor: "I'm glad you had greater ambitions than just selling junk."
    Danse: "Once I saw what the Brotherhood had to offer, there was no comparison. Anyway, about a year after we were posted to the Prydwen, Cutler vanished on a scouting op. It took some convincing, but I was able to persuade my CO to let me assemble a squad and search for him. It took almost three weeks, but we tracked his team down to a Super Mutant hive. Those wretched abominations had slaughtered everyone but Cutler. He should have been so lucky. The mutant bastards used their FEV to change him into one of their own kind. He wasn't Cutler anymore. I had to... it was my duty to... put him down."
    The Sole Survivor: "Are you sure there wasn't anything you could do to change him back?"
    Danse: "The FEV effect is irreversible. There was nothing anyone could do."
    (Danse's dialogue)
  91. 91.0 91.1 Richard Grey's audio diary
  92. The Vault Dweller: "{1001}{}{FEV}"
    Lieutenant: "{1104}{LIEUT60}{The Vats are where the FEV is stored, and where you normals become one of us. Of course, some die horrible, excruciatingly painful deaths, but well, those are the breaks.}"
  93. The Courier: "Where did you come from?"
    Lily Bowen: "I grew up in Vault 17. I never even saw the sun until I was 75 years old - that was when Super mutants raided the Vault and carried a lot of us off. Yes, Leo, I'm getting to that part! They made me one of them, and they put me to work in an army that was going to conquer California."
    (Lily Bowen's dialogue)
  94. The Master
  95. Fallout events.
  96. 96.0 96.1 Huntersville memories
  97. FEV research log #5
  98. FEV research logs; FEV research log #112
  99. FEV research logs; FEV research log #148
  100. FEV research logs; FEV research log #57
  101. Events of The Catalyst
  102. 102.0 102.1 The Lone Wanderer: "My father's work? How is that relevant?"
    John Henry Eden: "The purifier your father helped create has the ability to provide clean water to the whole of this "Capital Wasteland". With a simple modification, it can be used to distribute agents that destroy mutated creatures upon ingestion. In time, we could eliminate all mutations in the Wasteland at the same time the good people of the world regain their health. I need you to make the modification necessary for this to succeed."
    (John Henry Eden's dialogue)
  103. 103.0 103.1 The Lone Wanderer: "I'll do whatever I have to if it means getting rid of mutants."
    John Henry Eden: "I was hoping you would see it my way. If the water purifier can be activated, it can be used to distribute toxins that will eliminate any mutated creatures upon ingestion. The longer it runs, the cleaner the world becomes. I need you to see that it starts running, and that the necessary modification is made."
    (John Henry Eden's dialogue)
  104. Take it Back!
  105. Deacon: "I miss Capital Wasteland. You can actually drink the water there."
    (Deacon's dialogue)
  106. FEV lab terminal entries; terminal, Subject CM-153
  107. The Sole Survivor: "Consider it done."
    Arthur Maxson: "Look, I realize you're eager to take the fight to the Institute, but it will have to wait. The Brotherhood cannot allow those abominations to have a nuclear arsenal at their fingertips."
    Preston Garvey: "Those Super Mutants have been raiding across the Commonwealth for years. I'm glad to have the Brotherhood's help clearing them out."
    Arthur Maxson: "Now... we have a vertibird on standby, fully armed and ready to depart. Use it to carry our message to Fort Strong and wipe those dirty mutants from the face of the earth. Dismissed."
    (Arthur Maxson's and Preston Garvey's dialogue) Note: This is the reaction line should Preston Garvey be the active companion during the quest Show No Mercy.
  108. Brian Virgil Personal Log 0176
  109. Institute BioScience terminal entries; FEV lab entry terminal
  110. Fallout 4 loading screens: "The Institute's experiments with the Forced Evolutionary Virus, or FEV, ended when Doctor Virgil went rogue and fled into the Commonwealth."
  111. Institute Advanced Systems terminal entries; terminal, Personal Notes
  112. Fallout: Brotherhood of Steel Manual/Background: "But the story of FEV doesn't end there. Even after the war, an isolated group of scientists began experimenting on soldiers with an advanced form of the virus [FEV-2]. The results were promising... but the surviving soldiers got wise. They rebelled, killed all of the scientists and locked down the facility. Relocating themselves and some high-tech equipment to a new base of operations, these soldiers took it upon themselves to become the unofficial peacekeeping force of the wasteland... they became the Brotherhood of Steel. "


  1. Fallout Bible 0: "2. Does FEV really cause sterility? In Fallout 1 it seemed like the answer was a resounding yes, and a number of reasons for this were given by Zax and Vree. But then in Fallout 2 after you take Marcus to the Cat's Paw he says "I hope she doesn't get pregnant" and says that the FEV doesn't make mutants go sterile, it just makes it take a few years "to get the juices flowing again". Moreoever, the deathclaws in Vault 13 were infected with FEV and yet they are able to reproduce. So, does the FEV cause sterility or not?
    FEV causes sterility in some creatures. FEV does cause sterility in super mutants and ghouls - Marcus' comment in New Reno was a joke only (and it was an inappropriate one, for which I apologize for). For other creatures, however, the FEV does not cause sterility - in fact, it may actually speed up their reproductive cycles (in tandem with potential drawbacks). Known species that can reproduce after being mutated with the FEV include most species of rats, the mantises (who are known to have bred so fast they cover the Salt Lake City area like blankets), the radscorpions, and the deathclaws. This is only a partial list."
  2. Fallout 2 Official Strategies & Secrets p.26: "Many years ago, the Master, an insane doctor who attempted to become master of all humanity, tried to create guardians through gene splicing. The original Vault Dweller, your ancestor, stopped him before he could complete his plans. Unfortunately, some of his extraordinarily tough creations have oudived him and continue to roam the Wastes. Centaurs and Floaters are often found together, as though they feel some sort of kinship for one another."
  3. Fallout Bible 5: "Chris Taylor: Actually, a dip in FEV has a chance of modifying Intelligence, but it doesn't always increase it. Some people do gain increased intelligence, a larger majority lose intelligence and most people remain the same. It also depends if people have enough radiation damage to be turned into ghouls or super mutants."
  4. 4.0 4.1 Fallout Bible 3
  5. 5.0 5.1 5.2 5.3 Fallout 3 Official Game Guide Game of the Year Edition p.42: "Super Mutants"
    "The Super Mutants that infest the urban ruin of Washington D.C. originated in Vault 87. Those unlucky enough to have reserved space in Vault 87 soon found themselves forcefully taken to a secure part of the Vault, where they were locked in airtight chambers and exposed to a concentrated form of the F.E.V. The Overseer and his security force had no real idea what to expect; they were simply following the "plan." When the exposed Vault dwellers started transforming into Super Mutants, nearly the entire Vault population had been exposed. Those who hadn't yet metamorphosed knew what was coming, and, well...it didn't end well for humanity.
    The dwellers of Vault 87 were turned into Super Mutants in 2078, and have been a presence in the Capital Wasteland ever since. Most of those original Super Mutants have long since been killed. But whether it's because of the nature of the F.E.V. they were exposed to, or a simple underlying human instinct, the Super Mutants of the Capital Wasteland are obsessed with the preservation of their own species. Super Mutants are asexual and incapable of procreation, so their only way of reproducing is to kidnap other humans, drag them back to the Vault 87 chambers, and infect them with F.E.V. And so they have done, for nearly 200 years.
    Super Mutant society is loosely hierarchical, with the weaker (most recently transformed) Super Mutants generally giving way to the stronger. The Super Mutant hierarchy, as defined by the Capital Wasteland contingent of the Brotherhood of Steel, is as follows: Grunt, Brute, Master, and Behemoth. Generally speaking, the Super Mutants of the Capital Wasteland get bigger, stronger, and dumber as they age. The Behemoths are so strong and savage that they’re the only thing feared by the other Super Mutants."
    (Fallout 3 Official Game Guide faction profiles)
  6. Fallout Bible 0: "2235 The Enclave experiments on deathclaws, attempting to create special fighting units for waging war in hostile environments."
  7. Fallout Bible 0: "2076 January 26 Using batch 11-011, experiments are conducted on raccoons. Same results are noted, but the attempted escape of several infected raccoons causes Major Barnett to terminate the escape... and the test subjects. Two pairs of raccoons, however, are unaccounted for."
    "Note: Scott Campbell and Chris Taylor intended these escaped raccoons to form an intelligent animal community NW of the Glow called the "Burrows." This location was never implemented."
  8. Fallout Bible 0: "2102 May 22 Increasing mutant attacks on Harold's caravans cause Harold to get so pissed he finances one of the first adventuring parties of Fallout to try and find out where these dagnab mutants are coming from. Consulting with a scientist and doctor at the Hub, a man by the name of Grey, the two of them decide to join forces.
    2102 June 23 Richard Grey's Expedition [including Harold] finds the Mariposa Military Base and the Expedition is scattered and defeated by mutants at the base. Grey is knocked into one of the vats of FEV by a robotic arm, and Harold is knocked unconscious, only to awaken later out in the wasteland.
    2102 June 27 Harold, already mutating, is found by traders and taken back to the Hub. His former caravan partners and employees, horrified by his condition, abandon him and he is soon left without even two bottlecaps to rub together.
    2102 July Richard Grey, now horribly mutated by the virus, crawls from the Vats covered with FEV and in terrible pain. Barely able to think or perceive his surroundings, he crawls into the Vat control room and begins his audio log. He fades in and out of consciousness, sometimes for days or weeks at a time.
    2102 July-Nov Richard Grey begins to acclimate to his condition, and begins his first tests of animals by exposing them to FEV. These experiments and his growing awareness lay the foundation for his plans for the Unity and the master race. He takes the name, 'the Master.'"
  9. Fallout Bible 0: "2102 Nov The first human victim wanders into Mariposa, and Grey consumes him.
    2102 Dec Grey continues his experiments on wanderers that enter Mariposa... with no success. The creations are flawed (due to the radiation counts in their bodies), making them big but incredibly stupid, and Grey consumes them rather than letting them live."
  10. Fallout Bible 0: "2103 January The Master discovers the problem with the influence of radiation on his mutations, and he begins to choose his subjects more carefully. The first classic super mutants are born, butt-scratching animations and all. He begins his plans to build an army."
  11. Fallout Bible 0: "2103-2130 Throughout this period, the Master begins slowly gathering test subjects, willing or unwilling, from local human stock. The Great Winter of 2130 and the scarcity of human subjects make building his army difficult."
  12. Fallout Bible 0: "2131-2135 The Master begins ordering his super mutants to gather human stock from caravans. For many years, the caravan disappearances are blamed on monsters in the desert, and even when the abductions begin to occur on Hub caravans, the deathclaws are blamed. The super mutant army grows."
  13. Fallout Bible 0: "2137 Master begins to mass-produce super mutants. Only about one in six or one in five attempts are successful, and of these successes, only half seem to last to go on to be part of his growing army, called the Unity."
  14. Fallout Bible 0: "2152 As their influence slowly spreads throughout the wastes, the Master finds humans, doomsday cultists, and rather than dip them in the vats, he demands their obedience as spies - their leader is a man named Morpheus, and he pledges his followers to the Master. Morpheus and his cultists form the future core of the Children of the Cathedral."
  15. Fallout Bible 0: "2156 The Master sees advantages in establishing a benevolent "religion," the Children of the Cathedral, and using them as spies in settlements throughout the wastes. Missionaries from the Children of the Cathedral spread slowly across the wasteland, acting as eyes and ears for Morpheus and the Master."
  16. Fallout Bible 0: "2155-2156 After capturing a caravan of strange-garbed travelers (Vault dwellers), Master learns the location of the Boneyard Vault, the future site of the Cathedral. He conquers the inhabitants and sets up operations there, and the human cultists begin to use the Vault as their powerbase. Within the Vault, the Master learns of other Vaults, and realizing their human occupants are ripe for transformation, begins to send out patrols to Vault locations in search of these other Vaults."
  17. The Origins of Fallout: "A virus was genetically altered to treat and repair DNA altered by the Human Immunodeficiency Virus. Like all good things, it also had a drawback: it was engineered to alter specific gene segments in living cells, but sometimes it would change the wrong patterns, causing unpredictable and rapid mutations. So, of course, a government agency put two and two together and realized that this virus could be programmed to insert itself into the Human genome, altering it to whatever ends they wished – and with the threat of global war looming over them, they wished for a Captain America-style super soldier. So, as the story goes, the military base – which would become the Glow – was a research facility to create this super virus, and they were on the cusp of great success. I tried to greatly hint that this research had gotten out, and that this information leak is possibly the catalyst that caused the missiles to be launched. That also explains why the Glow is still a smoldering radioactive crater. However, even nukes couldn’t stop this virus. When the bombs hit, some heavily irradiated versions survived and drifted on the nuclear winds all over the world. The virus that was created to manipulate core DNA structures to yield stronger, bigger, faster, and more aggressive people found its way into all life outside of the safety of the Vaults. The virus had mutated so profoundly that it was able to affect mammals and even certain insects. It wasn’t genetic mutation – it was a mutated virus causing genetic modification..."