Angel (and by extension, demon) wings are funny things. A bit of a celestial's being essence made corporeal, not something made for touching unless a bond of trust has already been forged. Like sharing one's vulnerability, if said vulnerability could be held and caressed. Aziraphale is awed by the privilege, made humble by the sweet whimpers and stammered reply.

He kisses back, one hand slipping from feathers to shoulder so he can hold on as he pulls himself into Crowley's lap, getting even closer. His other hand keeps stroking those ephemerally soft feathers. "Beautiful," he whispers between kisses. "I want to touch every feather."