I remember reading a long wincest fic, it was in season 5, and ruby was still alive. Dean and Sam were at odds. Sam found a D/s store and bought a beginners bag. He gave it to Dean and told Dean to think about it. Dean called Sam on the phone and told him to lie on the bed with the lights off. Sam did. and Dean put the collar on Sam, and said it starts when Dean says, and ends when Dean says. Dean tied Sam up and "whipped" him and Sam got hard. and after a little while they had really hot, rough sex. Then Dean felt really guilty and took the collar off Sam. Sam was sad, Dean said they needed some time apart, but Sam didn't leave the town. Dean and Sam were crying a lot. After a couple days or so they got back together and had more sex. ;) around there they captured, tortured and killed Ruby. There is a scene in a diner, Sam isn't aloud to talk, and Dean feeds him. Sam is tied up. then they stopped the apocalypse, and Dean and Sam were going to ask to marry each other or something... I think thats all the details i can remember. it was on lj and it was bottom!Sam thanks!