Crowley figured out it was all just names for sides long ago, and it didn't take him much longer to realize which side he wanted to be part of. This one, here, with the best angel and the worst demon, or maybe the other way around. It all depended on perspective.

Crowley's perspective is currently that Aziraphale's neck needs a few more kisses, which he tends to accordingly. "You sure about that?" he teases. "I can name any number of occasions when they've been...effective..."

The word turns into an innuendo in its own right, punctuated by a small nibble on Aziraphale's shoulder.