Olivia strolls over to an ambulance to collect Walter, who's sitting there glumly. He's so beside himself that he has turned down an offer of soup from a paramedic. "This is because of what I did to all of you. This is because of me," says Walter. Olivia doesn't have much of an argument to make.
They're back over to Cameron's apartment and Walter is still berating himself for the experiments on thirty-seven innocent children. "I just turned you into numbers, numbers in my head. I didn't follow up on a single child, not even you." Olivia's basically "Speaking of that, shut up about that" and says Walter told her before that the doses were so low that none of the children's abilities lasted any longer than twenty-four hours. Walter can't explain that, but he has come to the conclusion that Cameron must be doing this inadvertently and therefore possibly not aware of the damage he's causing, but Olivia's not buying that: "This is purposeful. I can feel it."
At the steps of the apartment, Olivia makes Walter wait outside (he doesn't like it), presumably because he won't like being surprised by Dr. Crazypants all these years later. Walter bargains for her cellphone so he can call Astrid "to check on my project," and it sounds like he's lying to cover up his plans to look at online porn, or at the very least finally pass that Plants Vs. Zombies level that's bedeviling him.
Olivia heads up to Cameron's apartment and knocks, and the door is opened by "Mark Little" (aka Cameron James) -- he's wary, but he invites Olivia in when she says she has a few questions. In what seems a foolish mistake that I don't buy Olivia making, she leaves Little by the open door when she casually says she's actually looking for Cameron James. He bolts and starts racing down the few flights of stairs to the lobby, where Walter, evidently tired of having had to wait for thirty seconds, is pushing the buttons on the elevator. Cameron collides with him, and the two of them fall. "Cameron?" says Walter, on the floor, and Cameron is absolutely horrified to see Walter. The metal light fixture starts swinging, a nearby door swings back and forth.
Olivia makes it down to the first floor, and she angrily throws Cameron up against the wall, demanding to know why he's doing this to her, but he doesn't know who she is -- at least not until Walter says, "Olivia, please don't kill him," and he realizes she's Olive. Olivia thinks he's only pretending not to know what she's talking about, but he insists he hasn't thought about her in years. Well, you don't have to go that far, Cameron. Girl's got feelings! Walter brings up the astral projection, and Cameron calls him "Dr. Freak" and shouts, "I haven't being able to astral project since you stopped shoving needles in my arm when I was seven years old! Now all I have are the bad side effects!" Olivia's got to stop him from ripping Walter's head off, and then Cameron does his best to calm himself down, since any time he has any kind of anxiety, metal starts flying.