After their fiasco with the crazy chef, Sam can’t seem to get something out of his mind. Dean. More specifically, Dean under that spell. He was whiney and cute and everything Sam had wanted in a dog since he was a kid.
So, he starts acting differently- starts cooing whenever Dean stretches or flops down onto a motel bed. He starts carrying a bag of candy- rewards him when he does something Sam likes. It’s a quick slope, as Sam grows more and more overt- with Dean seemingly none the wiser.
Eventually, it makes its way into their sex life, and by then, if Dean didn’t realise what he was doing already, he did now.
Sam had him on his back, on the bed, wrists either side of his head with his hands balled into two makeshift paws. Sam had wedged a squeaky toy between his teeth and told him that if it makes a sound, he’ll stop.
Sam’s riding him, hard but inconsistent, focusing only on his own pleasure. Dean looks up at him with big, wet eyes, panting hot around the thin plastic and twitching from head to toe.
“Such a good boy, Dean.” Sam moans, grinding his hips in a figure of eight. Dean’s eyes roll back and Sam can see only the whites as he fights the instinct to clamp down his jaw. “My doggie- always does what he’s told, so perfect.” He hums.
A couple tears slip from the corners of Dean’s eyes and down onto the pillow from all the effort. He’s whimpering from the base of his throat and whining all nasal and high. Begging.
“Is doggie gunna cum?” Sam coos, slamming himself down, hard, over and over and over.
Dean begins to frantically nod, his short hair slicked to his forehead with sweat, cheeks flushed and red. He’s so hard, so close, it’s unbearable.
The toy makes a slight whistle.
Sam’s face blanks. He stops instantly- mid rise. “Oh dear...” He says, dodging Dean’s scrambling hands as he clambers off. “I guess we’ll have to try again next time.”