Disclaimer: I do not own Supernatural.
When Sam had packed his bags and stood in the doorway their father had said, "If you go now, don't ever come back."
Dean saw the surprised anguish in Sam's eyes because he'd never meant to go that far, to never see them again. But John had given the ultimatum and Sam wavered.
He looked at Dean standing in the small kitchen and Dean couldn't make his mouth say what it should. He couldn't say Dad, just let him go, let him have his dream and I love you. Call every day, okay Sammy? Dean couldn't say it because he didn't want to let Sam go either and John's way was the only way he could see to keep him. So when Sam looked at him for help or support or understanding or something he'd been silent.
And then the moment had passed and Sam was silent too. He didn't look at them again as he shouldered his duffel bag and climbed the rickety stairs to the small bedroom he shared with Dean so he could unpack his dreams.
- - -
In the following weeks, Dean wished he'd said those words that stuck in his throat. Sam seemed so empty.
It was in the way he could hardly get up in the mornings, not because he was so tired but because he'd fallen into apathy and he just didn't care. What was there to get up for anymore? But he'd look at Dean's pleading eyes and he'd pull himself up.
It was in the way he no longer fought their father. He did what he was told without asking all the questions he would have just weeks before, questions that were often very relevant, and they suffered without them. But Sam didn't speak them and if they were in his eyes, well, Sam hardly looked them in the eye anymore so they couldn't be blamed for not hearing them.
It was in the way Dean could tell that Sam's gun felt heavier to his brother. So that when a pissed off poltergeist came straight at his little brother, Sam didn't raise the gun fast enough and he bled all over the floor.
But mostly, it was in the way that as Sam lay there, half-conscious and bleeding, he said, "Dean, it's okay. Let me bleed. There should be blood on the outside too."