"Someone could get hurt," Sam said concerned.
"I thought that was the idea," Dean shot back with a smirk.
All too typical Dean, but his brother had changed, and the very idea shook Sam to his core. He had always had this image in his head of Dean as a stubborn as hell, never lay down soldier, but the events of the past few years had started chipping away at that. Though Dean never really showed it, hiding behind his joyous façade, things had irrevocably changed. The brother who had gone to hell for him, was not the brother that came back.
He hid it well, fooling everyone around them, but Sam knew his brother. He could recognize those moments when the memories gripped Dean in place despite his best efforts to hold them off. Sam quickly realized what was going on as Dean's behavior got more reckless, taking unnecessary risks and punches. His brother tried to keep the memories away through distraction, using the pain to fight off the bleakness of his thoughts. Sam may have understood the reasons behind his older brother's behavior, but there was no way he was going to stand aside and let Dean get hurt. If Dean needed the pain to keep him sane, then Sam would just have to give it to him himself.
It hadn't been easy to talk Dean into this. The older Winchester never wanted to admit that he needed something, or acknowledge that he had any kind of weakness. He especially didn't want to admit such a thing to his younger brother. However, Sam refused to be dissuaded, and managed to convince Dean that doing this in a controlled environment would be both safer and more beneficial.
So there they were, Dean lying tense across the bed as he waited to see what Sam would do. While the younger man tried to psych himself up to do one of the things he had sworn to himself never to do, hurt his brother. Still, he had to admit the thought was tempting. To do something to mar the perfect skin that was hidden underneath Dean's clothes. To in some way mark his brother as his.
Flipping open his pocket knife, Sam gave Dean a warning look to stay still, before carefully cutting away the fabric that covered him. Pulling away the pieces of the shirt that remained, he gazed hungrily at the now bared flesh. He teased the cold edge of the knife down slowly, leaving sensitized skin in his wake. Sam drew patterns and lines in faint white, barely scraping the tissue, only to cut in deeper painting a line of red along his brother's pecs and stomach.
He heard Dean's choked gasps and looked up to meet his aroused eyes, pupils blown with pleasure. Then returned his stare to the liquid flowing down the sculpted body before him. Unable to resist he leaned down to follow the path with his tongue and tasted his brother's blood. He caressed the skin with his mouth, sucking deep bruises and bites down the line of Dean's stomach. Gliding the knife back up the length of his body to tease his brother's shoulders and neck, Sam took his mouth in a hungry kiss and ground down against his hard crotch. Yes, this was definitely better.