I wrote this story a long time ago but I've been out of the writing game for a while due to some personal issues so I haven't posted it. This story switches Sam and Dean's ages but I kind of think Sam is still Sam and Dean is still Dean. Here's how I think it would have played if Dean were younger.
I don't own Supernatural.
Dean is six when he learns the truth. Sam doesn't want to tell him. Dad takes him, gives him his first gun and his eyes light up when he hits every bottle that Dad lines up for him. Dean learns everything that night.
When Dad tells him how Mom died and explains the importance of what he does when he's gone for days at a time, Dean listens and he believes.
He's too young to recognize the resentment that sparks in Sam's eyes on that day.
Xxxxxxxx
Dean's nine the first time he hears Dad and Sam fight. They're screaming at each other and he's heard enough to know that they're fighting about him.
He blocks it out because he can't stand it. He doesn't like them fighting but he can't do anything about it. They don't listen to him when he tries to stop them.
Xxxxxxxx
Dean's twelve the first time he sees something supernatural. The spirit terrifies him to his very core but at the same time it doesn't and when he holds the shotgun the way his dad taught him, when he pulls the trigger and the spirit disappears, he feels that rush and there's no going back for him.
Afterwards, school doesn't seem so important. It makes him feel restless. He's never liked school but now it just seems pointless.
Later, he can pinpoint that moment, when he had pulled that trigger, as his turning point. His epiphany. Everything changes for him.
Sam doesn't like it. It makes him angrier, makes him fight even harder against Dad. Dean doesn't know what to do about that. They're still fighting about him. He's stuck in the middle of it but he they never hear him.
But he knows. He knows that this is what he'll do. He knows that he won't be like Sam. He's not book smart like Sam. He doesn't like school like Sam. He doesn't like staying the same place like Sam.
Xxxxxxxx
Dean is fourteen when he finds the acceptance letters. They're Sam's. All of them and afterwards, Dean is terrified that he's going to lose Sam, that Sam is going to disappear off to college and he'll never see his brother again.
Sam doesn't go. He doesn't mention college. He stays and, even at fourteen, Dean understands perfectly well that Sam is only staying for him.
He's always loved his brother but he loves his brother a little more because of this. But Sam…Sam is even more resentful towards their father. Sam's eighteen and they don't fight quite as loudly as they had when he was thirteen, Sam even tries not to in front of Dean but Dean still knows they fight.
The tension is constantly there. Dean doesn't mention it, doesn't mention the letters or Sam's unspoken decision not to leave. He thinks that will only turn into another fight.
Xxxxxxxx
Dean is sixteen when he convinces Sam he should leave. It's not just about the tension. It's not just about the fights or the growing hatred Sam seems to be cultivating for their dad. It's about not being selfish. It's about Dean not being selfish.
That's what he thinks he's being, anyway. He's known Sam only stayed for him for a long time now and he knows Sam isn't happy, probably never will be.
It's probably the most painful thing he's ever done and Sam argues against it. He doesn't want to leave Dean alone with Dad. Dean goes on the offensive, tells Sam that he doesn't hate Dad the way Sam does, tells Sam that he can't take the constant fighting anymore every time Dad finds a new hunt.
Sam eventually sees it his way. He promises he'll keep in touch and Dean sees the guilt in his eyes when he leaves.
And Dean does lose his brother then but at least he's not feeling guilty or selfish.
Xxxxxxxxx
Dean is eighteen when he graduates from high school. He only finishes because he had promised Sam he would.
He's eighteen when he goes on his first solo hunt and when he burns the bones of the spirit and saves the lives of the people living in that house, he feels a bigger sense of accomplishment than he had when he'd been handed his diploma.
He doesn't tell Sam this when he calls but he thinks Sam knows anyway.
Xxxxxxxxx
Dean is twenty when the dreams start. For months, they are his constant companion. He dreams about fire, about a pretty blond woman he doesn't know.
He's twenty when his dad disappears, when Sam's college apartment burns down, killing his girlfriend, Jessica, who is blond and pretty.
Dean is twenty when his brother comes to find him. He doesn't tell Sam about his dreams either. He doesn't say that he's pretty sure that he'd been seeing Jessica die for months.
Sam is still unhappy, and the resentment towards their father is still there and Dean thinks that there is no such thing as a happy ending for them. This, having Sam with him is as close as he can get.