[Believed or not, the smile doesn't waver - Dean is a liar but a good one, unshakeable when it matters, solid the rest of the time. He doesn't look away.]

Sunshine, I got a lot bigger problems'n you hanging around. I ain't got the time or the energy for fear.

[Both of which are true. Dean is wary of the Marquis, aware of him, but he's a man with Hell hanging over him, with nothing to lose, and on a mission that will kill him if he fails in it. So he smiles, and he bluffs, and he slips on to the end:]

Should I be?