Any sound that Crowley can elicit from Castiel is like a delicious sin. He's so very responsive and Crowley wants to catalog every single one. There's an open almost innocence to them and Crowley knows that he isn't faking a single bit of this. He's not sure that Castiel even can.

The compliment earns Castiel a warm chuck. There's no real teasing or malice behind it. He's simply amused at the angel's frank honesty over it. He leaves a series of warm kisses around the mark he's made, far more tender than he really should allow himself to be, but what is this all about if not indulgence?

"Oh." He can't help the note of surprise. He really hadn't expected Castiel to be so easily forward, but he's just full of surprises, isn't he?

Crowley hums and presses his nose under Castiel's jaw. "That--that's just fine, Cas." The nickname falls from his lips, familiar, yet not at all.