Human!Cas gets drunk one night and becomes so maudlin he tells Dean how Naomi mocked him for having a crack in his chassis.
I love the crack in your chassis, Dean growls, and he flips Cas over onto his belly and spends the next half-hour worshiping his ass crack with his touch, his mouth, his tongue, licking it, lipping it, kissing it, until Cas is so oversensitized and hard that he can’t even form proper words.















