Disclaimer: These characters are not mine. If they were, they would all be getting therapy, and lots of it.
Warning: implied character death
Sam Winchester knew what was important and what wasn't. After all, it had been drilled into him all his life.
Well, okay, when he was little, he wasn't exactly sure what was important, except that it had something to do with what his Dad did. It was secret, and other people wouldn't understand, so they had to keep things to themselves. It was important to stay quiet so no one would know two little kids had been left alone (even when their father didn't come back for days and days), important to never draw attention to themselves (even if that meant going to school with a fever, because they couldn't risk someone phoning home about absences), important to never tell strangers anything (especially the ones who asked "Are you sure you're ok, honey?").
When Sam was old enough to be told the family business, he found out that it was important to start learning things so he could pitch in – things like how to recite exorcisms in Latin, and how to use a knife against something that was fighting back with teeth and claws, and how to dig up a grave. Mostly, he learned that it was important to avenge the death of a mother he didn't remember.
He had to be stoic about it, though. It was important to remember that he was a Winchester, and that Winchester men (the only kind left) don't talk about their feelings. They talk about the best kind of rifle for hunting black dogs, and whether or not spring-heeled Jacks might migrate, and whether or not vampires are real. If they (well, Dad or Dean) have been drinking, they might talk about the demon that killed Mary Winchester, but they don't talk about the wife and the mother that they missed.
Winchesters save people and hunt things, and that meant not staying in any one place for too long. That was way more important than having a dog, or friends, or any place to call home that wasn't a car.
Since home was a car, there wasn't any point in keeping things that weren't important. There was just no room. The trunk of the Impala could accommodate weapons, extra gasoline, rock salt, stolen hotel towels, a first aid kit, and a suit for Dad to wear when he needed to look like somebody he wasn't, but there was no room for things like novels, or tapes that weren't Dean's, or the rock Sam had picked up at a river that one day he and Dean had spent splashing and playing around in the water like the kids they were. Sam knew it was a sedimentary rock, but he hadn't said anything about it, because, well.
As he grew older, Sam thought that maybe, just maybe, there were other things that could be important, too.
For a while he thought soccer could be one of those things. It was good exercise, lots of running and coordination, it was practically training, and Sam actually liked it. But it wasn't really training, Dean patiently explained to him, and time spent playing soccer was time that wasn't spent hunting. Sam fought against that, a for a while, and then he stopped. Dean was probably right, it wasn't important.
Sam hoped school could be important. Sam really liked school. It was important not to draw attention to themselves, right? For a long time, that meant going to school. He knew better than to form any attachments, or to tell the truth in his "What I Did This Summer" essays, but apparently it was all right to actually enjoy being in school, so long as he wasn't too obvious about it. Developing good research skills seemed to be acceptable, since they could be applied to the hunt. Even his father agreed with that part.
What Sam's father did not agree with was all the rest of it. Why should Sam bother with chemistry when he already knew the supernatural properties of salt and iron and silver? Who needed to learn history, when every small town was furnished with at least one grandmotherly type who was more than eager to tell you who was murdered in the old house that no one lives in anymore? What was the point in learning biology, when all of the fuglies lived and died by their own rules?
Sam really struggled to convince his father that school was important. It seemed (to Sam, at least) like it was, especially when he took his PSATs, and looked at the kinds of schools he could get into with scores like his. He dreamed of wandering the ivied halls of Harvard, or maybe a sunny campus like Stanford.
By this time, Sam wasn't too surprised to be informed that his dreams weren't important. Since Dean had dropped out of school at seventeen to focus on hunting, Sam could do the same.
What was important was saving people, hunting things. Sam wondered sometimes why he couldn't be one of the people who got saved, at least for a little while, but he knew better than to ask.
Sam checked to make sure he was doing everything right. He hadn't said anything to Dad or Dean, because they don't talk about things. He hadn't talked to anyone else, either, because no one outside the family would understand. He wasn't leaving a note, because Winchesters only write in journals, and what Sam had in mind was hardly journal-worthy.
He'd made sure to get at least two towns away from his father and brother, since the police were sure to show up at some point, and he didn't want to draw their attention to his family.
Thanks to his training, he knew what gun to use, and how to use it. He wasn't carrying ID or anything else that would leave any record that he'd ever even existed.
He just hoped that Dean and Dad would be at least a little proud of him, since he'd tried his best to do what was important.
Feedback, please. It's the only way I'll learn.