Sam was sick. He was twisted up all wrong inside, fucked in the head probably before Yellow Eyes even entered the picture.
It had become something of a universal truth. Sam was intrinsically bad, Dean was his conscience. It was the core of their relationship. Sam was something Dean had to clean up after, had to watch carefully or risk the end of the world.
Yeah, it hurt when Dean looked at him like he wanted to hunt him, but Sam knew it was his own fault. The guilt was almost as bad as Dean telling him he wanted to kill him. Almost. He didn't blame Dean for telling him the truth. So when Dean checked and double checked where Sam was going, and why doesn't he let Dean do that, and Sam you're not in charge because last time you tried to make a decision you let the devil out -- so when Dean doesn't trust Sam, he gets it. He did that to himself.
(he'd ruined Dean just like he ruined the world he was a fucking disease and Dean should run he should kill him Sam should make Dean kill him)
And when Dean ditches Sam the first chance he gets, going out, Sam, don't fucking leave, Sam, wait for me, that's okay, too. And maybe Sam is a little jealous that Dean can get away from him, because he wants to ditch himself. He wants to crawl out of his skin and not remember who he is or what he did and feel like a person. But he's Sam fucking Winchester, and he doesn't really get a lot of privileges.
So what, Sam would always be Dean's fuck up little brother, so what he was kind of disposable at this point. So what Sam needed Dean more than Dean needed him. So what.
If he knew it would be so much worse.
Because Sam had been keeping secrets since he knew what secrets were.
He'd always known he was off. He'd felt it in the way he got so angry at the littlest things, in the way John eyed him after a particularly nasty fight, in the way he'd stare at his gun a little too long. But mostly, he felt it in the way he'd look at Dean the way Dean looked at pretty girls.
He'd tried to fix it. He'd tried to fix it with pills, with a knife, a bullet. He tried to fix it with magick before he realized how stupid that was. He tried to fix it in the middle of a hunt, but Dean was much too careful to let that happen.
Eventually, he got scared enough to book it. It was the hardest thing he'd ever had to do. He left Dean, he left Dad, he left every safety net he'd ever known. Sam was alone.
But college had been a decent band aid. After he stopped binge drinking and snapping at everyone who looked at him wrong, he managed to forget (not really). He passed it off as a phase. He Moved On.
And then he met Jess.
She was beautiful and patient and kind and nothing at all like Dean but Sam wanted her. In a way he hadn't wanted anyone since he moved out. She was probably the best thing that had ever happened to him. She was his everything. She showed him normal, she showed him what love was supposed to be like. She was his proof of insurance. His, hey I'm strait and I can be okay, card.
So he got his shit together. He set up his future. He was going to be a lawyer.
He was lying to himself. He still felt the same, deep down. He knew the kind of person he was. You can't change your DNA. People like him don't get college, or beautiful girlfriends, or normal. People like him didn't deserve it.
(he didn't deserve Jess and he knew it he shouldn't have touched her he'd ruined her he wasn't worth that what was wrong with him what the fuck was wrong with him)
Dean was clueless. He was lost and alone and scared and Sam wanted too much from him.
And Dean was so fucking clueless.
So he left (again), death trailing behind him like it fucking belonged there.
(it probably did)
He left his girlfriend, his friends, his scholarship, like the world revolved around him and no on else mattered, but Dean didn't see.
He never saw, with Sam.
So he got back on the road, he killed Jess like he killed him mom.
Sam's skin was smothering him and he felt like he'd been living too long.
He knew, he fucking knew he should leave Dean, should make him see what Sam did to the air around him, what he'd done to Dean. What he'd done to himself.
(didn't he see, though? Hadn't the apocalypse shown him?)
But he was selfish. Had been all his life, he just couldn't figure out how to stop.