Crowley lifts his hands up to cradle Aziraphale's face, to lead him into the kiss. Aziraphale is an angel, and his innocence is part of what Crowley finds so endearing about him. No reason for the demon to just leave him floundering about. He leads the kiss, deepening it slowly, parting his lips so that Aziraphale's licks can be met with his own tongue.

After all, lust is a pretty fantastic sin. Not Crowley's favorite sin---that is now and always will be sloth, which is the best sin of all time. But it's a good one, nonetheless. Even better in this exact moment, holding onto the person Crowley has loved for thousands of years.