ETA: Found: dean killed Mary, john makes him eat salt/starve/being whipped to control him
Fic found: was Sins of the innocent by reapertownusa.
This is a very dark fic, and starts out with dean basically being raped by a gang of demons he has lured to a warehouse, after which he and John kill and burn them all. Dean shot and killed Mary when he was four, because a demon "infected" him after breaking into their house. To keep him in control so the demon inside him does not make him kill anyone else, John forces Dean to continuously eat salt, drink holy water, and get whipped. He is not supposed to talk to anyone because he might infect them too. He goes to school for a bit but later stays at home after teachers get suspicious about his bruises. He gets less food than Sam, who after a while starts smuggling food to him when John does not see. After a few years they go to stay with someone who is not John (might possibly be Pastor Jim). Dean is in a terrible shape.
I think I have messed up with the screen/unscreen settings - if your comment does not appear it is due to this (sorry). Thank you everyone that helped me!
This is a very dark fic, and starts out with dean basically being raped by a gang of demons he has lured to a warehouse, after which he and John kill and burn them all. Dean shot and killed Mary when he was four, because a demon "infected" him after breaking into their house. To keep him in control so the demon inside him does not make him kill anyone else, John forces Dean to continuously eat salt, drink holy water, and get whipped. He is not supposed to talk to anyone because he might infect them too. He goes to school for a bit but later stays at home after teachers get suspicious about his bruises. He gets less food than Sam, who after a while starts smuggling food to him when John does not see. After a few years they go to stay with someone who is not John (might possibly be Pastor Jim). Dean is in a terrible shape.
I think I have messed up with the screen/unscreen settings - if your comment does not appear it is due to this (sorry). Thank you everyone that helped me!