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| ||For the synth prototype child created by Shaun, see Shaun (synth).|
Shaun was less than a year old by October 2077. On October 23, at the outbreak of the Great War, his parents take him and manage to flee to the nearby Vault 111 as the atomic bombs begin to fall on the Commonwealth. Unaware of the true purpose of the Vault, Shaun and his parents become frozen in cryogenic suspension. Approximately six months following their internment, a revolt occurs and the staff abandons Vault 111, leaving those frozen within unaware of what had occurred.
The cryogenically preserved Vault participants would remain undisturbed for around 150 years until the Institute discovered records regarding Vault 111. At this time, the Institute was desperate for genetic material unaffected by the radiation-ravaged wasteland for their Third Generation Synth project. The infant Shaun represented the best source for uncorrupted DNA and so the Institute set about to acquire him.
Sometime in 2227, the Institute dispatched their mercenary, Conrad Kellogg, to Vault 111 to secure Shaun. Along with two other Institute technicians, Kellogg revives Shaun, along with one of his parents. Shaun’s parent was unwilling to part with their son and put up resistance. Kellogg then promptly shoots and kills Shaun’s one parent, leaving the other in cryogenic suspension and terminating the life support on the other frozen Vault participants. Shaun’s surviving parent, eventually known as the Sole Survivor, would later escape Vault 111 in 2287.
Shaun was then raised by them as one of their own, later nicknamed "Father" for his role in providing the DNA required to complete the synths. In time, he became the acting director of the Institute. The Sole Survivor can find Shaun and can choose to side with him or not.
Shaun is absolutely, stalwartly convinced the Institute is the only hope for humanity, and tries to subtly convince the Sole Survivor of this. He gives them highly unlimited access to the Institute, introduces them to the personnel of the Institute and even trusts them with missions to seek rogue synths. His feelings about the Institute as the future and last hope of humanity is almost to an extreme point - he is possessed with an unmistakeable fear of the surface and the potential threats of the Commonwealth to the Institute, desiring to take humanity further underground and away from the radiation, mutant and danger infested surface world.
Having not been raised by his parents and only by technology, Shaun lacks compassion - though he has a strong desire for humanity to survive - and feels indifferent upon remembering the death of one of his parents. He simply refers the "incident" as "collateral damage" which potentially angers the Sole Survivor. However, he also reveals it was his personal choice to awaken the Sole Survivor from cryostasis, not an error of Vault 111. He struggles somewhat with being reunited with the Sole Survivor in the Institute, ironically seeing one of his parents 'younger' than he is, and wondering what they could have shared if the circumstances had been different.
It is later revealed that he has a very aggressive form of cancer and one of the endings is to take his place as Director of The Institute after his death, which was his primary wish all along.
If The Survivor decides to eradicate The Institute and bring the young Synth with them they will receive a holodisk recorded by Father and given to them by the synth Shaun after being interacted with. The cybernetic Shaun tells The Sole Survivor "I didn't listen to it, so I dunno what it says, but I think it's important".
It is revealed that the young boy was reprogrammed to believe that the player character was their parent, as the first meeting between the synth and player character (who was led to believe that the synth was their missing son) caused the synth to become confused and call for help. The reason for him being reprogrammed is explained by the real Shaun in the holodisk, saying "I would ask only that you give him a chance. A chance to be a part of whatever future awaits the Commonwealth."
Interactions with the player character
|This character is essential. Essential characters cannot be killed.|
|This character is a temporary companion.|
|This character is a permanent companion. They grant the - perk.|
|This character is a doctor.|
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|This character can repair items.||Repair cap: -|
|This character can modify weapons.||
|This character rents beds.||Cost: - caps.|
|This character starts quests.|
|This character is involved in quests.|
- Shaun's crib mobile plays the Baby Steps theme from Fallout 3.
- According to Todd Howard, Shaun's appearance will alter based on the couple's appearance, similar to how James' appearance alters slightly depending on the Lone Wanderer's race in Fallout 3.
- A copy of "You're S.P.E.C.I.A.L." can be found in Shaun's room before and after the war lying next to his crib. It can be collected by the Sole Survivor after the war and allows player character's choice of 1 point in any one SPECIAL stat.
- If chosen the Institute ending, a grave marker will be seen in the Institute's main room in front of the Robotics section. The player character will then say "Goodbye Shaun" if interacted with.
- Shaun can be damaged without him turning hostile.
- Shaun can also be killed right after meeting him; though doing so will lock one out from the Insitute storyline and make them permenantly hostile.
- The Shaun seen in the Memory of Kellogg is not identical with Father but is in fact the child synth prototype.
- In his Director's quarters room at the Institute there is a Trifold American flag in a broken case on a shelf (the same room as the synth Shaun) This is possibly intended to be the one seen in the Pre War starting scenes on a shelf in the player character's House, perhaps kept as a memento by Shaun. Nearly all furniture items in the Institute are new so it sticks out and is carefully placed on the shelf. However on emerging from Vault 111 and entering the Sole Survivor's home there is also a broken version of the Trifold American Flag on the ground by the shelves. Therefore it is not certain if it is intended as the same item or some other reference.
Shaun appears only in Fallout 4.