Dean sat in the cold, uncomfortable hospital chair, listening to his brother talk about hunts and complain about Lucifer. Every so often Sam would flinch or react to something, Dean supposed, Lucifer had done, and Dean thought that if he didn't know what he did know, he too would believe that Sam belonged in there.
Against the whiteness of the hospital clothes, every mark and scar on Sams skin became 80% more visible. Dean couldn't help but notice the faint scars on Sam's wrists and the few faded track marks on the inner side of his right arm.
Everytime he saw the scars or the tracks he remembered. He remembered so vividly the day he found Sam on the floor of the motel bathroom, and the day Jess called him up and told him that his brother had OD'd. Dean couldn't believe it. His little brother doing drugs, no way, that wasn't him, she must have got the wrong person. He had thought.
But of course she hadn't, and after the initial shock, came fear and panic, until he was practically yelling at Jess down the phone to tell him what hospital Sam was staying at. And when he saw him, his baby brother, for the first time in 2 years, laying unconscious in a hospital bed, he was angry. Angrier than he had ever been. Angry with his father for casting Sam out like that, acting like he didn't even exist just because he chose to take a different path. He was angry at himself, for getting drawn in with his fathers pathetic views, for not contacting Sam, and for ignoring him when he called. He was supposed to protect Sam not ignore him.
And when Sam awoke he was shocked to see his brother. And Dean asked him why he had done it to himself, why he'd attempted suicide again. Sam persisted that it wasn't an attempt, it was an accident, but Dean couldn't believe him, and he couldn't risk it, so he told the doctor that it was, what Dean to this day still believes it was, a suicide attempt. And Sam was sent to the psychiatric ward.
Dean remembered his fathers face when he had told him where he'd been. Yes, his father was worried at first, but that didn't last. Once John knew Sam was safe, he made Dean vow not to go back there. He told him that Sam wasn't part of the family anymore, that Sam had been the one who chose to leave them, so why should they go to him whenever he slips up. Dean hates himself for listening to his father. He never did visit Sam again.
Now, as he sits with his broken shell of a brother, he promises himself to never leave him again, no matter what. He doesn't even care what Sam has done in the past, he is his baby brother and he's not going to leave him with just the devil for company.