She notices him behind her, and asks for his help. Instead she gets a little lecture: "You understand right now how important it is to be seen. Your life depends on it, me seeing you right now," he says.
Then he yanks her up, effortlessly, but grabs the gun from her holster as he does so, and then he points it at her. Olivia's all, "Hold up, you're dying!" and asks him to let them try to heal him.
But he's -- rather understandably -- skeptical, given a) how he was brought up, as a freak scientific experiment, and b) the fact that he has, you know, recently murdered people. "If you're here to help me, it's because I have value to the military. And they don't want the long-lost Experiment 69545 to self-destruct. Not when they've found him again. Olivia says she has nothing to do with the military; she just wants to stop the killing.
And here comes the diatribe: Eugene starts talking about watching other people live their lives, watching them fall in love. "To be looked upon by the right person, to connect, and to see in their eyes kindness. Happiness ... and recognition. That's when you exist," he says. Olivia's radio -- which she's been unable to answer for a few minutes -- crackles with Lincoln asking if she's OK. She ignores it to tell Eugene that she works with a scientist for the FBI in a Harvard lab. "If anyone can hope to undo what they've done to you, she says, but Eugene interrupts to snap, "I lived my life in a lab! I am not going back!" Swing and a miss, Olivia. She tries telling him that if he treats himself again even once, it might kill him.
By this point, Lincoln and the other agents are storming up the stairs because they haven't heard back from her. Eugene bolts as the agents come crashing in, and Olivia warns them that Eugene has her gun.
So Olivia and the agents race around looking for an invisible man, but there's no trace of him, somehow. I wouldn't mind an explanation of how he escaped -- given that he does have a physical form -- but Olivia finds her gun set down and figures he's gone.
Downstairs, outside, Olivia tells Broyles that the dogs have been through every floor twice, no trace of the guy, so Broyles gives the order to let everyone back into their homes.
Everyone starts filing back in, and -- does no one really notice the guy who then comes OUT of the building and is walking in the opposite direction of everyone else? Especially given that the dogs are now going nuts again in the back of their police vehicle? The agents look around futilely to find the source of the dogs' excitement but come up with nothing. Maybe let the dogs out again?