He Ain't Heavy
Warnings: Various season spoilers. Big brother!Dean, Protective!Dean, Hurt!Sam
Dean was four years old the first time he held his little brother in his arms. He sat beside his dad, pillowed against his side, arms cradled, while his mom placed the tiny little baby in his arms. Sam was wiggly, his skin was a weird color of white, and he smelled, but the first time he smiled was when he laid in Dean's arms. Dean took pride in the fact that he could make his baby brother smile almost any time he was upset, except when he was stinky and mom or dad had to change him.
Dean took full responsibility for holding Sam as much as he could to make him smile, including the nights after the fire when Sam would just cry and cry.
Sam would stay in Dean's arms for a long time, until he was about four and John decided that Sam was too big to be carried around by his brother like a baby. So Dean didn't do it again, at least, not in front of his dad, until Sam was thirteen.
They were on a hunt for what John had believed was a wendigo or something along those lines, but Sam had argued that it wasn't. All signs had pointed to a Sasquatch, which usually didn't bother humans unless they bothered it. Which, some dumb deer hunters had done. And soon, so were the Winchesters. Dean wanted to laugh at his dad, tell him that Sam was right and Big Foot was just pissed off, but the creature swung a branch that hit Sam, knocking him against a tree and knocking him out. After trying to get him to wake up, Dean picked his brother up in his arms and cradled him against his chest. He was starting to grow, with a little more muscle than the little toddler that Dean used to heft around, but Dean was prepared to carry him back to the car.
Dean didn't have to cradle Sam again for a long, long time. He cradled his face in his hands, wiping blood from his eyes. He held onto Sam's arms when the headaches from visions became too much. But it was that rainy night in Cold Oak that Dean held his very tall baby brother in his arms as he drew his last breath and slipped away from him. And when Dean sold his soul for him, he was able to hold his brother again, living and breathing.
Times came and went and walls were built up between Sam and Dean. Hurtful things were said, backs were stabbed, and lives were lost. Dean watched as Sam fell into hell and all he had left to remember him by was his duffle bag of clothes in the back seat of the Impala. This wasn't something that he could hold Sam through and make everything better.
Things continued on with many speed bumps and potholes. Souls lost and gained, shots fired, hunters becoming the hunted, on and on. Mary came back into their lives and was greeted not by a four-year-old boy and his tiny baby brother, but a forty-year-old man and his not so tiny but still little brother. And when they followed her into the alternate universe to save her and Jack, Dean had a feeling things weren't going their way. Especially when he was forced to watch as Sam got his throat ripped out. Dean tried to go to him, to see him, but Cas stopped him, telling him he didn't have time.
Dean walked along with the rest of the group in silence. He didn't get to hold his baby brother in his final moments.