Okay. So. Sam has a right to be Emo. He has a right to want normal, and he has a right to crave normal and he isn't a horrible person for going after that.
Okay so we know that Sam and Dean and John moved around at least a little bit when the boys were growing up. We know that they lived in motels [Something Wicked] and it's safe to say that they lived in the car at least while driving around. They probably lived in a few apartments but I doubt it was very many because most apartments require cleaning deposits, insurance deposits and first and last months rent up front. Not the kind of stuff you can use a credit card on. That's ignoring trying to get electricity in the place and other things that require money like that.
Now even if they all stayed somewhere long enough to get an apartment they probably still stayed in a motel while John, and maybe Dean too, got enough money scraped together. There are apartments out there that don't require all that stuff. They're usually the places in high-crime neighborhoods; the places that are glorified motels and have hookers and drug dealers and other people like that living there.
Imagine you are in sixth grade, the beginning of middle school. Now imagine that you are Sammy. You don't remember ever owning a single piece of clothing that someone else hasn't worn first. You don't have a phone number and you wont invite anyone over cause you don't want the other kids to know you live in a motel or, during those rough stretches without money or a way to get it, a car.
You never wear short sleeves even though it's hot because you have scars that make the teachers call the police, you aren't allowed out alone, you aren't allowed out after dark and you have to be home every day at four no matter what. You always bring your lunch to school and it's almost always PB&J and when you don't it's because there isn't enough money to eat this week.
Your clothes smell weird and have weird stains and you can't tell anyone it's because a demon gooped all over you a month ago and the smell and stuff wont come out. You've stitched up your father and brother and seen them both almost die more times than you watched The Simpsons, you feel overwhelming terror every time a cop pulls over the car and you live in fear of the day they ask if they can open the trunk.
Now tell me you wouldn't want to change all that.
Growing up Sam was always the new kid at every school. He probably had no friends and didn't play with the other kids during recess and was always the weird kid that no one talked to or liked. He was the kid who sat against the wall and never talked and who the teacher always praised for his good grades and who always waited in the classroom for his big brother when school was out. Kids don't talk to that kid.
Sam doesn't like having to try and remember what his name is this month or his new social security number this week. He doesn't like worrying himself to the point of vomiting when Dean and/or Dad are late coming home. He doesn't like being afraid of the police and the teachers and the school nurse. He doesn't like being afraid to eat over at someone's house because he's afraid he'll eat too much.
In all of Sam's 18 years with John I don't think he ever spent a night at a friend's house. Not once. John wouldn't feel safe enough to let that happen. Eighteen years old and Sam probably has all the social skills of a rabid hamster.
Dean has his "mission" and that helps him live the life; if Sammy's safe he can deal with not having any friends or anything like that. Everyone thinks he's cooler than fuck anyway, as long as he can get laid when he wants to it's okay. Sam doesn't have this. Sam has nothing to help him "deal" with this life except for a brother and father who probably get overbearing with their single-minded need to keep him safe.
Sam wants what he sees as a safe life. He wants a stable address and friends and food in the fridge. He wants to have a teacher for more than a month and a job that's not day labor and a friend who can come over to his place when he wants to. He wants to be able to study with someone he isn't related to if he doesn't understand something. He wants to not worry about speaking Farsi for half a month because of an awkward exorcism.
Sam never again wants to get picked up for shoplifting by the father of the meanest bully in his class, never wants to see kids from his school at the mall while he and Dean are getting sandwiches and juice-boxes from the Home Base* van.
It's not about hunting monsters. It's not about living a life where he ignores all the bad things that shouldn't exist and hoping they'll go away. It's about wanting something stable and something that makes him even a little like anyone else. I'm almost sure that if they had a home base or if Sammy knew any other kids like him that things would be different. If he had someone else to talk to that wasn't his blood he probably wouldn't mind everything as much as he did.
Dean will never know what it's like to be Sam: to desperately want people to like him and to feel like complete scum every time someone gives him that look.
Dean was the kind of kid who could make acquaintances with anyone and be fine. He could worm his way into the jocks, hit on the nerd-girls, and feel perfectly at home with the law-breaking troublemakers. Dean's adaptive and has the kind of confidence that will get him accepted anywhere.
Sam is not. He's kinda shy, sorta awkward, nerdy as fuck but not in the way where he raises his hand in class all the time. Like most teenagers he doesn't think there's anyone else like him in the world, unlike most teenagers he knows for a fact that he's right. He doesn't listen to their music and he doesn't have the free time or money to go watch their movies and stay home and watch their shows.
It's not that Sam wants to abandon John and Dean, it's not even that he doesn't want to save people from the things that go bump in the night; he just doesn't like being looked down on for all the things that come along with it.
[*Home Base Youth Services is the name of the homeless shelter for youths up to 21 here in Phoenix. Aside from the shelter they also have a van that comes to the large mall here and they give sandwiches and juice and bottles of water to the kids who live there. They come by every night at the same time and they don't lecture or anything. If you're there they give you a bag unless you refuse it. They don't make you ask because they know it's a pride thing. There are things like this in lots of places going by lots of names.]