The comment gets a raise of Prior's eyebrow and he can tell just from this short interaction that Fitzjames is a little looser than he's seen before; even near-death, with coldness threatening all around, he hadn't managed to looks nearly as relaxed (although that might not be saying much at all).

"Why's that?" He manages to shave the sharpness from the question, but he still wonders what purpose there was in the other man saying as much. What about this party makes it un-Prior-like?