Hey everyone, so this time I'm looking for a possessed story that I could have sworn I bookmarked, but apparently not.
In it Sam is whammied in a hunt and gets possessed by a canine spirit I think and starts wanting Dean. Bobby chains him up in the basement so that he can't get to Dean. Sam starts to be able to scent Dean, I think Dean might be giving off pharamones or something.
In the end Bobby holds Sam back  by the chain while he 'mates' with Dean so that Sam won't hurt Dean.

ebcdic

onelittlesleep