“With this Perk, you have gained the attention of a Mysterious Stranger, who will appear to help you from time to time. If your ally is lost in combat, do not expect him or her to be replaced.”— Fallout & Fallout 2 description
Only in hostile random encounters, there is a chance that the character will gain a temporary ally in a leather jacket (male with a male character and female with a female character). The unidentified stranger's details depend on the player character's level.
$ \text{Chance of appearance }%=30+(2\times\text{Luck}) $
The Mysterious Stranger remains on the map of the random encounter even after the end of the fight, until leaving. The stranger can be spoken to, but will not say much.
Unlike in Fallout, the Mysterious Stranger will now leave the map of the random encounter directly after ending combat. A few exceptions to this are caravan encounters, and encounters with a cave included.
If attacked, the Mysterious Stranger will attack back; however, he will be friendly again during the next hostile random encounter.
The inventory of the Mysterious Stranger is different at each random encounter.
If the Mysterious Stranger dies, he will never come back.
The Mysterious Stranger perk in Fallout is stronger than in Fallout 2, since the Mysterious Stranger is already at their maximum statistics and their plasma rifle is more powerful in Fallout than the H&K G11 that the Fallout 2 equivalent has.
In Fallout 2, they can be encountered in any random encounter. This also includes simply stopping on the map, and entering the map via the inverted triangle at your location.
The Mysterious Stranger with a hunting rifle actually spawns shotgun shells as ammunition instead of .223 FMJ. As such, the Mysterious Stranger only has the 10 shots already provided in the magazine.[verified]
In Fallout 2, if the game is saved during a random encounter when the Mysterious Stranger is still on the map and then reloaded, the Stranger will remain in place.[verified]
“Gives you your own personal guardian angel... armed with a fully loaded .44 Magnum. With this perk, the Mysterious Stranger appears occasionally in V.A.T.S. mode to lend a hand, with deadly efficiency.”— Fallout 3 and Fallout: New Vegas description
Mysterious Stranger Coming
Mysterious Stranger Missing
If the last target at the end of V.A.T.S. sequence has 150 health or less, there is a 10% chance that the character will gain a temporary ally in a fedora and overcoat that will finish off that target using his unique .44 Magnum.
In the Fallout 3add-onMothership Zeta, when first arriving aboard Zeta, having the Mysterious Stranger perk opens up a new line of dialogue with Somah, with the option "Maybe, if we're lucky, a friend of mine will show up to help us."
In Fallout 3, "mesmerizing" non-player characters with a Mesmetron in V.A.T.S. will sometimes make the Mysterious Stranger appear, resulting in him killing the victim.
The Mysterious Stranger will sometimes seek out other hostiles while in V.A.T.S., after he has killed the targeted one.
His appearances have a counter ("Mysterious Stranger Visits") that is displayed randomly during the loading screens of Fallout 3, and on the Pip-Boy 3000 under the "Stats tab - General" in both Fallout 3 and Fallout: New Vegas.
In Fallout: New Vegas, the Miss Fortune perk functions in the same way as this perk, but with different effects in combat.
Both the Mysterious Stranger and Miss Fortune perks can be chosen by the player character, but the characters will not appear together in the same V.A.T.S. sequence and taking both perks will not increase the chances of either one appearing.
When interrogating Silus at Camp McCarran, if he is being attacked by the Courier using V.A.T.S., Silus will be killed by the Mysterious Stranger should he appear. In this event, Carrie Boyd will not respond in any way to Silus' death.
It is possible to attack and even cripple the Mysterious Stranger by accident in V.A.T.S, but this seems to have no effect whatsoever.
The Mysterious Stranger can be incapacitated by nearby explosions, sending him flailing about.
If the Mysterious Stranger/Miss Fortune appears in gas-filled area, their gunfire will ignite the gas and hurt the player character and enemy alike.
In Fallout: New Vegas, after the Mysterious Stranger or Miss Fortune appears 15 times, the Friendly Help challenge is completed, increasing the probability for them to appear in combat.
There is a chance for the Mysterious Stranger to miss all 6 shots from his .44 Magnum and the target will be completely unharmed.
He may be seen reloading his weapon if he runs out of ammo. However, the Mysterious Stranger is never given the chance to finish.
PCPlaystation 3Xbox 360 The Stranger will sometimes be positioned unfavorably. This can include being stuck in a wall, being placed in water, being placed near a cliff, etc. This can result in his "death" (unconsciousness) or inability to effectively attack the enemy, or even in some cases to kill the player character if they are between him and his target. Because the Stranger never attacks, even if all enemies have died, he will be forever trapped inside the level geometry and the trigger to return the game to normal never happens. The only choice is to load a previous save.[verified]
PCXbox 360 During V.A.T.S., it is common to hear the Mysterious Stranger jingle, even if he does not appear. This most likely happens at times when he would have appeared to finish off your enemy, but you killed the enemy instead. He may also have been affected by the bug above in some of these cases.[verified]
PCPlaystation 3Xbox 360 Sometimes when the Mysterious Stranger appears, he does not shoot. He will just stand there, leaving you helpless. Another variant makes the Stranger reload his Magnum for the duration of his attack. If it jams, he may not attack at all. This also happens if his target is killed prematurely by an explosion or by you or a companion. V.A.T.S. will remain active for an extended time, leaving you open for attacks by any surrounding enemies.[verified]
Playstation 3Xbox 360 While in the Operation: Anchoragesimulation, the Mysterious Stranger will sometimes appear and then lie unconscious. When the V.A.T.S. sequence ends, gameplay will return to normal.[verified]
PCPlaystation 3Xbox 360 At times, the Mysterious Stranger will aid you during V.A.T.S., but there will be a 5-10 second delay between killing the target and returning to normal gameplay. This can pose problems when fighting multiple enemies, as they will continue to attack both you and your companions during the delay. On occasion, this bug may cause normal play to not resume.[verified]
PCPlaystation 3Xbox 360 Sometimes, the game can freeze in the zoomed-in style of V.A.T.S. when the Mysterious Stranger appears, making him stand there and watch.[verified]
Xbox 360 Occasionally, the game may register that the Mysterious Stranger has appeared (you receive a progress update) but he does not, nor does the opponent die. You remain frozen in V.A.T.S. unable to move or die.[verified]
“Who is he? Why does he help? Who cares! The Mysterious Stranger will appear occasionally in V.A.T.S. to lend a hand, with deadly efficiency...”— Rank 1 description
The Mysterious Stranger may appear in V.A.T.S.; he will then fire a single shot from his .44 Magnum to instantly deal a massive (but not always instant killing) amount of damage.
The jingle for the Mysterious Stranger is a similar version of the one heard in Fallout 3 although more high pitched. There are several variations of the Mysterious Stranger's appearance jingle and disappearance chime, which are randomized when he appears to assist the player character.
The Mysterious Stranger will have vanished from the map by the time your character exits V.A.T.S., meaning that it is impossible to interact with him, though some companions will comment on his brief appearance. Nick Valentine especially will react to an appearance of the Mysterious Stranger if he is the Sole Survivor's companion at the time, and has the Mysterious Stranger marked as an open case. A briefing of the case can be found under Nick's bed in his office.
Unlike the previous games, the Mysterious Stranger's face is mostly obscured by his worn fedora.
The appearance rate is 10% for the first rank, 12% for the second rank, and 14% for the third rank. This does not change with higher Luck.
Though the Mysterious Stranger is always depicted with a revolver, the death animation for the target will be based on the weapon the Sole Survivor is wielding, so they may be disintegrated if you have an equipped laser weapon or gooified if you have an equipped plasma weapon.
Enemies will sometimes attempt (futilely) to attack the Mysterious Stranger during his brief appearances. This is most noticeable with feral ghouls, who will attempt to perform their flying tackle on him, only to end up passing through thin air and sprawling onto the ground.
PC If the Mysterious Stranger is hit by an attack that makes him stagger before he has fired his weapon, he might not end up getting a chance to fire. This appears to happen more often in confined spaces. This does not adversely affect his future performance.[verified]
PCPlaystation 4Xbox One On occasions, the Mysterious Stranger will appear too close to the target, preventing him from taking a shot and killing the target. This appears to be related to the game trying to place the Mysterious Stranger on the same level as his target. This does not adversely affect his future performance.[verified]
Playstation 4 If one targets a Vertibird in V.A.T.S., the Mysterious Stranger may appear, but will not shoot at the Vertibird.[verified]
Xbox One If the Mysterious Stranger appears while using V.A.T.S. on a ceiling turret, he will appear in the ceiling and will not damage the turret, This may also sometimes cause game crashes.[verified]
There were several unfinished drafts of a book by Mark Twain titled "The Mysterious Stranger", in which the title character claims to be Satan's Nephew and that he was actually good all along, and states that Earth's other name is ".44". The character in this series is labeled a "Guardian Angel" (the Devil is stated to be a fallen angel) and carries a .44 Magnum revolver. Though likely a coincidence, the comparison is interesting nonetheless.
Edit
