Two 12-year-old bullies are killed by some kind of fungal growth that causes corpses to explode in spores (killing hard-working and slack-ass morgue attendants alike). The Fringe team (it’s all Earth-1 this week) connect the fungus (which Walter names “Gus”) to the bullied kid, to whom Walter takes a particular shine, mainly because the boy, Aaron, reminds him of Peter. You know, Walter’s son who died when he was a boy. And, as Walter tells the skeptical kid, the other Peter, who came from the other universe, only to drown in the lake immediately upon the return trip.
The fungal growth is essentially a big neural system that has formed a psychic bond with the boy, what with hom feeling so alone. That means that attempts to destroy the killer fungus result in pain (or death) for the boy, and Walter doesn’t want to lose Peter again (or Aaron a first time). Fortunately, all it takes to break Aaron’s psychic bond with Gus is for Walter to give him a speech about how he actually isn’t alone.
Meanwhile, Walter’s feeling like he’s going completely insane, but at least he knows enough to try to hide it from the hard-ass head of St. Claire’s, who’s checking on him. Fortunately, he’s got a plan to fix it. Whatever it is, I’m sure it will be based on scientific OH MY GOD HE’S GIVING HIMSELF A FRONTAL LOBOTOMY. Olivia intervenes, at which point Walter confesses to having hallucinations of a man who’s calling for help. Olivia’s all, “Uh, you mean this guy?” and shows him a drawing she made (of Peter) of a man she’s been seeing in her dreams the last few weeks. Ol’ Bloody One-Eye Walter is relieved to find out that this reflection isn’t just his own psychosis. And now that they know this guy is real? “We have to find him,” says Walter. Looks like Joshua Jackson’s vacation may be coming to an end.