No, I'm serious, this is dark shit.  I'd put it in the "horror" genre. 

Some man had captured Sam and kept him locked up, and he called him "Pumpkin".  Sam began to lose any sense of identity.  The man had a surprise one day, and the "surprise" was that he was going to whore Sam out to all his friends.  I think Sam was dressed up in a slutty glittery outfit, it may have been purple.  At the party, Sam vomits, and the man rubs his face in it and makes him clean it up, erm, manually.

Meanwhile, Dean had quit looking for him and was drinking himself into oblivion.  They run into each other and I don't think they recognize each other at first, but Sam remembers some Latin exorcism that saves Dean.

It probably ends in wincest, since that's mostly what I read.

While I'm at it, I'd like any fics that show how much Sam and Dean depended upon each other as kids?  Maybe with Dean taking care of Sam growing up- kid/teen!Sam is LOVE.  In-character fics are preferred, though I realize schmoopy in-character Sam/Dean might be an oxymoron.  But I need that aforementioned horror with a side of schmoop, if you'd be so kind.

I hope I've been clear!  Sorry for the bipolar request.  

#1 FOUND: Promise Me You're Not A Dream  (It's an abandoned fic though)