Peter Bishop is a fictional character on the Fox television series Fringe. He is portrayed by Joshua Jackson. Peter Bishop is the son of Walter Bishop.
He is a genius with an I.Q. of 190, and an MIT drop-out with gambling debts. His presence is often necessary to keep his father lucid and to explain the confusing, scientific speech his father uses when explaining his discoveries. He was also responsible for keeping his father in a mental institution for 17 years.
He is not very fond of his father, as he wasn't around much during his childhood, but has warmed up to him after he starts to take care of him. He is given the post of civilian consultant to Homeland Security to make him officially part of the special investigations team. Several events regarding Peter's personal affairs suggest that he's involved in more than he is aware of.
He is possibly part of one of his father's experiments, as he remembers Walter wiring car batteries to his head and shocking him when he was a child. He apparently almost died from a rare form of bird flu when he was young, but he doesn't seem to remember this. In the final episode of season one, "There's More Than One of Everything", Walter visits Peter's grave, which lists his date of death as 1985; combined with Walter's assertion that he found a way to travel to a parallel world to regain something he lost, this implies that Walter's original son died of the flu and that Walter replaced him with Peter's duplicate from an alternate reality.
This is further hinted at in season 2, when Peter has a dream of Walter taking him forcibly from his bed when he was a child and when Rebecca (who can see people from the other universe described as a "glow") briefly sees Peter shine.