Peter Bishop grew up as the neglected son of a mad scientist.
After his dad's mental institutionalization, Peter aimed to make himself as different from his father as he could. He's a college drop-out that passed for several months as a chemistry professor, along with an intuitive mathematician with a gambling problem.
Peter is now a civilian consultant for the FBI.
Peter: Is this the map that we downloaded from Dr. Fayed's hard drive?
Alt Astrid: It is. Why?
Peter: We're in the wrong universe.
Walter: This is quite delicious.
Peter: Where did you get that?
Walter: In the car, uneaten.
Peter: What is the matter with you?
Walter: Oh, forgive my son. He's been in a mood all day.
Peter: I just figured "don't eat the evidence" goes without saying.