I was on Tumblr and I came across a headcanon that said - headcanon that right after the first time Cas kisses Dean, Dean will touch his fingers to his lips and give kind of a quirky half-smile and mumble "awesome" under his breath. And I felt the need to write something for it. So here you go :)
Cas looked at Dean with no small amount of adoration. He couldn't decide if this was what he wanted or not, but right now it didn't matter. He leaned closer to Dean and whispered the hunter's name before brushing their lips together lightly.
Dean's eyes widened. Cas pulled away with a small smile. Dean's hand came up to his lips. His finger tips ran over them and he seemed half-dazed. a small half-smile quirked at Dean's mouth and a hushed "Awesome" escaped him.