So it seems like it's kind of fanon to have pre-series Dean always trying to get Sam laid and such (or maybe I am hallucinating that? It's a possibility). Anyway, I actually think that Dean would be really super protective of virgin!Sam.
Like, okay, imagine
that maybe they're stuck in some small town, Podunk Nowhere. Dad's off on a hunting trip, but left them behind because he didn't really need them for this.
Sam is in school and Dean has to stay behind to look out for Sam, even though Sam is fifteen now, and Dean has been left alone to look out for Sam since he was eight, but whatever.
So to pass the time, Dean is trying to make it with this waitress at the diner by the place they're staying (Dean never calls it "home"). He has Sam meet him there after Sam gets done with school as an excuse to be there. Not that he really needs one.
The waitress, Cindy, (but spelled with an 's' and an 'i' to make it more exotic) is not that much older than Dean. Maybe twenty or twenty-one, but she has that world-weary jadedness of someone who knows that this is all their life is ever gonna be.
Dean drinks coffee and reads the paper and flirts until Sam comes in and walks up to the counter.
"Well hey there, sugar," Sindi says, suddenly all cleavage and leer. "What can I do for you?"
"Coffee, please." Sammy's completely oblivious, thank God. He turns to Dean then and says, "Are we gonna be here for awhile? I have some homework I want to get done."
"For awhile," Dean says.
Sam takes his coffee and sits down at a booth and Dean turns to Sindi. "What the hell?"
She ignores his gobsmacked expression in favor of saying, "That's your brother? I'd love to see what your Daddy looks like." She snaps her gum and winks at him. "No offense, sweetheart. S'just sometimes a girl likes a challenge, and, well. That's a challenge."
Dean turns to look at Sam again. He's bent over some giant textbook, brow furrowed, chewing the end of his pen.
"Find another one," Dean says as he turns back to Sindi, his voice tight and low. "He's fifteen."
"Really?" Sindi ignores the warning in Dean's voice completely. "Looks older'n that to me." And she has this calculating predatory look in her eyes that makes Dean's jaw clench.
"Well, he's not." Dean waits until he has her full attention again and says. "Stay away from him. Or you and I are gonna have a conversation, and I guarantee you won't like what I have to say."
"Whatever." Sindi walks down to the other end of the counter to flirt with a burly trucker. More power to her.
And the thing is, Dean isn't mad that Sindi doesn't want him. Dean knows he's pretty and he's never had to try too hard for willing company. It's not even that he's jealous of Sam. Jealousy has no place in their relationship. It's just that Sam is too young. Too young for women to be looking at him like that.
The bell over the door rings and a group of high school girls walk in. Dean watches them as they pick a table, and sees the moment they notice Sammy. The oldest gets the same predatory gleam in her eyes that Sindi had. Skank.
But it's one of the younger ones that gets up. She looks to be about Sam's age, and she's wearing her jeans low on her hips, a top that Dean's pretty sure shouldn't be allowed in school, and her walk shows she's jaded in a different way than Sindi. So it's skank-in-training, then.
The girl slides onto the bench opposite Sam. Dean can't hear what she says, but Sam looks startled, and his cheeks turn pink. The girl just smiles more.
Dean studies them as they talk. The last of Sammy's babyfat has disappeared from his face, and it's all sharp, intelligent angles now. And Dean knows that Sam doesn't have the body of a fifteen year-old. There's no way for them to train the way they do and not be built.
Dean knows what they want, too. These girls who are so interested in Sam. Because amazingly enough, this is the innocence Sam's been able to cling to, despite having Dean as a brother. It's obvious in the way he literally jumps when the girl reaches out and touches his arm.
Which just makes Dean insanely pissed. Sam hasn't got a whole lot of things to be innocent about, and he doesn't deserve to have Trampy McGee cut her teeth on him.
Sam should have a nice girl.
"C'mon, Sammy. Time to go," Dean says before he even realizes he's at Sam's table.
Sam looks flustered and relieved, which means that Dean did the right thing. "Did you pay?"
"Not yet." Dean hands Sam the keys. "Why don't you go throw your stuff in the car. I'll be right out."
The girl looks up at Dean as Sam leaves and flutters her eyelashes. "You're Sam's brother?" She touches his arm like she did Sam's and Dean steps back.
"Hold up there, Lolita."
She loses her smile.
"Stay away from my brother." He tosses a ten down on the counter and earns a dirty look from Sindi. Oh well.
Dean walks outside to see Sam stretched out in the front seat of the Impala, and the little punk is actually taller than him now, which is probably going to grate for a while. It seems that Sam grew up a little when Dean wasn't looking. He just doesn't know when the hell it happened.
What Dean does know is his job of protecting Sam just got a little bit harder.
So, yeah. That's what I was thinking. Anyway...