Hunger of Old Mouths by plutogirl10.

Slash.

Starts off slow. Sam and Dean go south, and run into a guy who wants to rule the world or something. I got to wondering if it was slash at all, or if I had misread the link. Then Dean goes and does something stupid, and loving, and exchanges his sould for Sam’s. The only way Sam can get him out of this is by possessing him, literally and figuratively. There’s blood ritual and semen sacrifice and it’s so beautifully done…slow paced and careful and lyrical and humming with love. It all works out right in the end, or as well as it can for a Winchester. Sheesh. Stuff like this can make you want to stop writing forever, cause, why bother when there’s this out there?

““You said my name,” Sam whispers rough in Dean’s ear, desperate for him to know. “Do you know that, Dean? Last night, you said my name.”

Whatever Sam thinks he should be feeling, it’s all replaced with total reverence when Dean makes the gentlest sound imaginable and bucks, shuddering apart in Sam’s arms, control finally gone. Sam feels every tremble imprint itself into his skin, they’re pressed so close together, and it carries him along with it, leaves him dazed. It takes him some time to register the sticky warmth clinging to his stomach and over his hand.”