He can probably sense the way her pulse is racing -- not because she's afraid -- he's had plenty of chance to hurt her in the past and he never as -- but entirely different reasons. Her chin lifts as she states in a defiant fashion.

"Who says any of this is a game to me?"

But isn't it? In a lot of ways their interactions have almost devolved into a weird form of flirtation chicken that usually ends when one of them (often her) pushes the other too far?