James is the father of the Vault 101 Dweller. The whole plot of Fallout 3 revolves around him and his mysterious disappearance.
James is the player character's father in Fallout 3 and is voiced by Liam Neeson. While there is no surname given, his appearance is set so that there is a family resemblance. At the start of the game, when the player is born, he is the first person the player interacts with and during the rest of the tutorial segment of the game, he acts as a very supportive father. Presumably to take the role of both parents following the death of his wife and the player's mother, Catherine. However, the game really begins when James flees from Vault 101 with no apparant motive. This goes against the wishes of The Overseer who now wants both him and the player dead, leaving little option but for the player's character to flee also.