Now that Walter and Olivia are united in their respective Peter-glimpsing insanities, they can work together! Walter has set up all kinds of video cameras to try to capture (for posterity) the apparition, and he’s calmed down now that he knows he doesn’t have to lobotomize himself. But Olivia’s feeling a little more stress, because she wakes up with some sort of energy coalescence in her bedroom.
Walter, eager to prove that he’s much too valuable to be recommitted to St. Claire’s (which is Dr. Sumner’s recommendation), ventures outside the lab as he and Olivia track down a former Cortexiphan experimental victim, I mean SUBJECT, who had some kind of astral projection ability. Cameron no longer has that, but involuntarily affects electromagnetic fields, meaning he can’t even go on a date with a woman lest he pull the fillings from her teeth. But seeing as how Dr. Freak (aka Walter) is not the intimidating presence he used to be, Cameron agrees to use that power to destroy the visiting energy bugging Olivia. But when it comes again, it manifests itself into a humanoid form that looks like Peter — to Olivia, that would be the man in her dream — so she calls off the energy assassination. Also, she got the sense that it didn’t mean her any harm.
So the energy coalescence goes away, right into Reiden Lake, where an actual, physical Peter surfaces. He knows about Fringe, and Olivia and Walter and everybody, but Fringe has no IDEA who this guy Peter is. But now he’s back, he’s at the hospital, so hopefully Olivia can figure out that this stubbly stranger is Walter’s son and the man of her dreams.