Warnings for underage sex and incest. Hurt!Sam, Comforting!Dean.
I hope you enjoy my twisted mind. :)

Dean tore through the streets, swearing and mutterin under his breath about stupid little kids getting their asses kicked for daring to touch his brother.
He'd been researching something for his Dad, who was in North Dakota, when he got the call. Sam's high school. Telling him that his baby brother had been beaten up, and was rather 'worse for wear'.
Dean didn't think he'd ever shouted so much abuse down a phone.
He actually felt a little bad after, because whoever he was on the phone to was just relaying a message, but that didn't excuse the fact that the message content was ridiculous.
Something was wrong here. Sam was four years younger than Dean, but he sometimes beat Dean in training - more times than the elder Winchester would ever care to admit. The notion that a bunch of fifteen-year-olds could beat him up was almost a laughable one,
Almost.
But not to Dean, not right now. Because Sammy was hurting. And when Sammy was hurting, Dean felt as if his world was beginning to fall apart.
He knew how he felt for Sam wasn't healthy, or normal. But he ate enough cheeseburgers and killed enough ghosts to know he wasn't healthy, and he wasn't normal.
No, society's views weren't what stopped him claiming his mate.
It was the fact that Sam was fifteen.
It was the fact that he was Sammy's big brother, he was supposed to protect him... Not fuck his brains out, like he wanted to.
It was the fear of rejection.
There it was, the big one. Dean was absolutely terrified that if he told Sam, his brother would say no. Worse, hate him, be disgusted by him.
No...better to let sleeping dogs lie. Hold back.
And pray to God that the boy didn't get any hotter.

When Dean arrived -in a mass of screeching tires and pissed-off hunter- he was directed to the infirmary, where Sammy was lay on a bed, crumpled shirt in a heap by his head. Dean's eyes fixated on his brother's slender, defined hipbone, thinking just how wonderful it'd be to nibble that delicate flesh... He shook his head roughly, trying to clear it. Now? Really not the time.
Sam's eyelids flickered, focusing wearily on Dean. "Hi, Dean."
"Sammy, what the Hell?" The elder settled himself on a crappy plastic chair, glancing at his brother's bruised face and stomach. "Why'd you let them do this to you?"
"I... I didn't want to fight them." Sam turned his face away, looking ashamed.
"So you let them make you their bitch instead? I'd rather be called in for you kicking some boys asses, Sam, than to collect you because you've been beaten up!"
"Um... Mr. Winchester?" The nurse, an older woman with silvery hair secured in a ponytail, smiled slightly, handing Dean Sam's backpack. "You're free to take him home... Although hospital would be a good precaution, as a few of his ribs may be broken. If he has any dizziness or nausea, take him in. He could have delayed concussion." He nodded a little, helping Sammy up as he winced and hissed.
"Thanks." He answered shortly, grabbing Sam's shirt. "C'mon Sammy, let's get you home."

Awkward was the only way to describe that journey. The car's atmosphere was so thick it could be cut with a knife. Dean was white-knuckling his way through the streets, while Sam stared morosely through the window.
When they arrived, he eased Sam down on the sheets of his bed, trying not to let his eyes focus on the slight peek of hair creeping out of the top of Sam's boxers as he sat on a chair beside his brother's bed.
"Sam... Why'd they beat you up?"Dean asked. He avoided my eyes as he answered - he was lying.
"They're kids, Dean. They don't need a reason."
"I'm only gonna ask you once more, Sam, and I want the truth. Why'd they beat you up?"
Sam swallowed, eyes closing, a red flush crawling up his throat as he murmured something,"Sorry Sam, I didn't quite get that. Speak up."
"I said... They beat me b-because I said I was gay."

Dean's heart had stopped, or was hammering far too fast. Either way, he felt too light -headed. "G-gay...?" He repeated, still in shock. "Who's the guy?" The idea with Sam being with anyone - especially a man- who wasn't him made his stomach turn. But he just had to ask, didn't he?
"Someone I can never have." Sam answered quietly, looking into his brother's eyes. Dean's breathing hitched, and he hardly dared to hope as he pressed a gentle hand to Sam's bruised cheek.

"I know the feeling..." Sammy's eyes widened infinitesimally, and he gently touched his lips to his brother's in the kind of sweet kiss he'd been waiting for. "I love you, Sammy."