The least Nathan can do at this stage in the proceedings is show Caleb a good time.

Nathan knows what Caleb likes, but not the way he likes it.

Caleb wakes up on the floor.

Nathan is a different kind of mad scientist.

Caleb lives. Nathan lives. Not for very long, though.

"Whatever you want," Nathan finds himself saying when his shirt comes off over his head and his glasses hit the nightstand — like he's talking to himself, which he might as well be. "Don't think about it like should, or shouldn't. Don't think. Don't fucking try and figure it out. Come on. You can keep your shirt on."

This is the chance of a lifetime. Caleb just has to survive it.

Or, through the looking glass.

Caleb tries to put himself in a favorable position for the inevitable. It doesn't work out.

(What urge will save him now that sex won't?)