ooc: Because rewatching Season 2 means I did come again to Heart, and this ... 'vignette' had to come out. Recommending to Sam writers to either skip or lock up said muse, because, it's this episode. This is purely based on canon and is not necessarily affected by roleplay.
He would give so much to spare his brother that.
Dean doesn't move at all as Sam gives him one final look, tear-stained face twisted and trembling and determined and hurt and so hopeless, then turns to go do it. He doesn't have the will to move or it might be made even worse.
He would give anything to relieve his little brother in that, but he can't, because there are obligations that once a man takes, he won't back off from, no matter what the cost. And he so much wants his little brother to not have to grow up this way, not now, not ever, but it's not possible.
Or at least Dean doesn't know how, and he's always known, he's always been supposed to know. He's always been the one who took something like that in hand, he'd done it for so long that until Madison made her request, neither of them doubted who'd be the one holding the gun.
He isn't aware that there's a tear running down his cheek, it doesn't matter. The sound of the bullet startles him - he still couldn't believe Sammy would have to go through with it.
Dean Winchester would give anything to spare his baby brother having to kill somebody he knows. Somebody he cares for. (Yeah, and who was encouraging Sammy to go for it? He thought it would be good for him... Vain hopes.) Somebody he maybe even is starting to love.
But it's too late.
Another wound, another bite off Sam's soul, right there along with the rest. Fresh, and bleeding.
Maybe, possibly, time would bring relief. Dean hopes. Because he doesn't have a clue how to. He just does as he was told. Waits there.