You Can Hear The Whistle Blow A Hundred Miles (слэш)

Sam leaves at the age of 15 to escape the homophobia of John and (he believes) Dean. Unable to force himself out of love with his brother, and resentful that John thinks him useless, he fakes his age and joins the marines. He's determined to prove that being gay, and being guilty of the crime of not being Dean, doesn't mean he couldn't hack it, like John's always telling him.
After years of excelling in the marines, mastering his psychic powers, and using his visions to protect his family long-distance, his destiny finally catches up with him and Sam is snatched from a botched covert mission by the YED.