Shaun

Shaun, also known as Father, is the son of the Sole Survivor in Fallout 4, the Director of The Institute, and also a potential antagonist, if choosing not to side with the Institute.

Background
From the appearance of Shaun, he was born around the summer of 2077. Just before the nuclear bombs hit The Commonwealth, he was taken into Vault 111, and put into a cryo chamber. He was kidnapped by two mysterious figures, one of them being Kellogg some 150 years later, from the arms of the spouse of the Sole Survivor. As Mama Murphy can explain to the Survivor, she can sense Shaun is still alive around 2287.

In 2227, The Institute discovered Vault 111, and with it the radiation-free survivors they needed to complete the synth project. He was abducted by its members and 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 may be forced to defeat him.

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. Having never stepped beyond the walls of the Institute in his life, he is left with a view of the Commonwealth that only reflects what he has been taught or heard.

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."

Appearances
Shaun appears only in Fallout 4.

Behind the scenes
In contrast, the Lone Wanderer, child of James from Fallout 3, was originally forced to slay their own father, but the part of the storyline was scrapped away.

Shaun (Fallout 4) Шон (Fallout 4) Shaun