- Jessica Holt: What are you?
- Dr. Walter Bishop: I'm human. What are you? Is this some sort of alien invasion? Are you a part of a strike...?
- Jessica Holt: No, I mean, what are doing here? Are you a doctor?
- Dr. Walter Bishop: The escalator is infested with nanites.
- Olivia Dunham: Nanites?
- Astrid Farnsworth: They are microscopic self-replicating robotics. There's a machine that's generating them.
- Dr. Walter Bishop: Despite their itty-bitty size, each of them is capable of storing a tremendous amount of energy, and it would seem they can be overloaded by the bio-kinetic energy stored in the cells of anyone infected.
- Peter Bishop: [bemused] You mean, these people's movement is what's activating the nanites?
- Dr. Walter Bishop: [snippy] That's what I just said. And the longer they are in the bloodstream, the more sensitive they become, so that the slightest exertion can trigger the overload.