[ It's like every nerve in Crowley's human corporation lit up like a Christmas tree, and he can feel every reverberation of it to his infernal core. Credit where it's due, human bodies were brilliant.

Crowley is sucking a hungry trail as Aziraphale goes on about arms races, feeling a warm sense of satisfaction as the angel says his name so sweetly, and he loves him all the more.
He'd originally just planned on teasing him, maybe slithering down and getting his tongue in on the fun; but the way Aziraphale asks makes it sound like he'd want more than just a bit of rubbing action there. ]

D'you mean other than my fingers? I can, I definitely can, if you'd like. I mean, if you're ready and all, no rush. Can just tease a little, go as slow as you need. Everything we're doing, been doing? Feels marvelous.

[ He's rambling, suddenly feeling all nerves. He doesn't want to push Aziraphale into something he's not ready for if he's misread the signals. Not the first time they got their wires crossed. ]