I cant find i fic that i read a little while ago. Dean left Sam after he set Lucifer free. ever since sam has been going through withdrawal for years. I remember sam was is a dinner and teenagers were calling him a junkie and the waitress was ignoring him. I think he called Dean at one point and Dean found him a in a car. They went back to Bobby's and found out Ruby put a spell on him to make it seem like he was going through withdrawal.
thanks in advance