Fringe: Season 3, Episode 15

3 - 15: Subject 13

Following from the second-season episode "Peter", the show returns to 1985 to recount events after Peter's abduction. Elizabeth (Orla Brady), worried that Peter (Chandler Canterbury) will attempt to kill himself trying to return to what he believes is his home, takes him to Jacksonville where Walter is conducting Cortexiphan trials on children. Walter finds young Olivia (Karley Scott Collins) has been able to cross to the parallel universe, believed to be a result of fear of her abusive stepfather, and sees it as a way to return Peter. When one of Walter's test causes Olivia to set the room ablaze from pyrokinesis, she runs away. Peter finds and meets her, and gives her confidence to trust Walter and face the fears of her stepfather. Olivia tearfully returns to Walter's office, giving him her sketchbook that shows her pictures of the parallel universe, her stepfather, and her and Peter together, but she soon finds that she inadvertently crossed to the parallel universe again. Walter warns off Olivia's stepfather, while Peter returns with Elizabeth to Reiden Lake and comes to call her "mom", a lie that eventually leads to her suicide. In the parallel universe, Walternate, having previously lost his resolve, gains new confidence, knowing through Olivia's sketchbook that Peter is in the prime universe.