Something beautiful. And in its way, this is something beautiful. Something shared with just them. Pleasure and love and intimacy---three things that neither of them have truly partaken in through their time on Earth. Oh, Crowley has been part of temptations before, but they've always been work. Sex and desire have never just been something he's wanted, something he's wanted to share. It's different with the angel. The angel makes him feel things, makes him love things.

He could do this forever. He could finish Aziraphale off with his mouth over and over again and never stop, and that would be good enough for him. At the same time, he wants to feel more of the angel, wants to share pleasure with him, wants to be with him. With that thought in mind, he breaks away from his shaft, kissing back up his stomach to reclaim his mouth with his lips.

He shares the sensation of being inside of a lover, of claiming them as your own. He also shares the sensation of being the one claimed, the one taking in the sensation, of giving. What do you want? he thinks to the angel. Crowley would easily do either with the angel, and gladly. It's all what Aziraphale wants.