Comfort isn't a thing demons do, or get, so Crowley at least can definitively say: no, no he never experienced comfort like this before Aziraphale, never. It was completely foreign to his experience. Still is, in many ways. There are reasons why he was so quick to believe the worst and despair on the train, and they have to do with tens of thousands of years of conditioning. There's no comfort for a demon, no forgiveness, no salvation, no anything.

No softness, no love--but those he allows himself, now, those he's taught himself to accept. It wasn't easy. But he needed them so badly. Needed Aziraphale that badly.

A lot in common, you and me, Crowley had once said, and not least of those was how damn alone they were, in different ways. But not anymore.

There's another thing countless time in Hell teaches you, and it's to savor the good things while you have them, before they're taken away. So Crowley finds it easier than Aziraphale does to push recent events aside and just be here, now, his angel in his arms and both of them where they should be, where they want to be. Everything else can wait. He's still upset, yeah, and scared. All those things. But they'll keep.

So he kisses Aziraphale long and slow, using this other language they speak to say all the things that words don't convey as well:

I'm here. We're both here. I love you. I love you. I love you.