Hoist by His Own Petard: Black believes Dr. Kramer either accidentally got infected or was experimented on himself. Kramer refuses to tell him anything
Screw the Money, I Have Rules!: At the end, Black ripped the check the Department of Energy gave him after using him to find Zero. The moment after he did that, an unknown person is calling his phone. Black decides not to answer it, but it keeps ringing...
The Reveal: Zero is Dr. William Kramer, who works for the Human Genome Project.
The Unreveal: Kramer was in the military, taking part in the 1994 Rwandan Genocide. But not much else is revealed.
Ungrateful Bastard: Knox helped Kramer when he was infected, and was killed for his trouble.