The Devil's Mark by ninhursag

The Devil's Mark - ninhursag
3.5 stars. A well-written if confusing dark fanfic. In an apocalyptic America Dean buys abused slave Sam from a flesh dealer five years after he disappeared aged sixteen. The story is very much off canon from the TV series although both Azazel and Ruby feature strongly.

"You fucked me over," Sam shouted. Dean heard the sharp sound of something breaking to pieces while he sneaked around the back. Holy water font had to be here somewhere. "You lied to me and you fucked me over like I was a fucking chess pawn."

Ruby's voice sent a shudder down through Dean's skin. She sounded like it was funny, like she thought these were good times. "Lying's kinda what I'm known for, man. But, if you actually think this one through, I didn't. You did get out and you did get to Dean, just like I promised you."
Source: http://archiveofourown.org/works/55089?view_full_work=true