Castiel isn't sure how to admit to himself that he is developing some fondness for Crowley. The torture is off-putting, but necessary, and his own hands aren't all that clean anyway. He does enjoy conversation with him; there are references and jokes that go over his head in a frustratingly/charmingly familiar way. And now, with Crowley purring against his skin and being gentle with him, that fondness is quickly increasing. It makes Castiel feel... appreciated. Not that he wants to admit it. He isn't even coming close to admitting it. He's indulging himself in sin and apparently tenderness with a demon, and that's it.

He smiles slightly and follows up Crowley's comment with a tentative bite, tentative only because he's new to biting people, not because he's uncertain of whether Crowley will enjoy it.

"I'm glad you approve." He sucks lightly at the skin, less interested in leaving a mark as he is recreating the feeling, which he had enjoyed.

As for his hand, he's far less confident about what he should do here, and he wishes he could ask, but he's afraid that might make him seem less appealing to Crowley, and it's very important that that doesn't happen.