Crowley's gaze meets the angel's and he gives him something that all demons know: a temptation. He tempts him with his gaze, with his body, with his fingers. He shares with him the sinful desire of lust and the want of touch. It probably isn't fair, sharing that with him right now, while they're in the middle of all of this, but he is so very tempted by the beckoning look in Aziraphale's eyes, he doesn't know what else to give him.

Want it. I'll give it to you. He croons to Aziraphale's mind.

He slips a third finger to join the first two in their movements.