Warnings: Unrequited love.
Sam didn't run off to Stanford because he didn't love Dean enough. He left because his love was twisted and wrong and he saw his big brother's face every time he came. He left because when Dean stumbled into countless motel rooms smelling like pussy he wanted to throw him down and mark him, claim him as his own. He left because he was stuck in Dean's orbit and if he stayed he'd be burned to ashes. Sam had no other choice.
