Sam tries his best to take care of Dean.
Dean, for the most part, ignores it. It keeps Sam busy and hey, whatever turns your crank, Dean figures. So he pretends not to notice it when Sam slips a new pair of socks into his duffel, or when his shirts come back suspiciously mended and bloodstain-free. He looks the other way when Sam starts handing him vitamins along with the aspirin. Okay, so he throws a fit when he comes back from the bathroom one day and catches Sam trying to sneak FiberSure into his coffee, but there's gotta be a line, he thinks, and he's pretty sure fiber supplements cross it.
The thing is, Sam just doesn't know when to give up. Instead of dropping off once he realizes his big brother isn't long for this world, Sam's efforts redouble-- like he's trying to counteract all the bacon cheeseburgers and hard liquor. Dean has this perverse urge to take up smoking, just to see what Sammy will trot out next. It's pointless, he wants to say. What the hell are you even trying to save? But when Sam pulls his morning beer out of reach and slides over a glass of orange juice instead, giving him those sad, anxious eyes, Dean drinks it and doesn't say anything at all.
It doesn't stop there, either.
After Dean's stint in Hell ("stint", right, like it was just a brief saunter there and back), Sam picks up right where he left off.
"Full," he complains, pushing a half-eaten plate of food across the table at Dean. What's left on the plate consists suspiciously of mostly vegetables, and Dean gives little brother the eye.
"I don't want your broccoli," he says, scooping up the last of his eggs-and-sausage combo platter.
"It's got cheese on it," Sam says, like that somehow makes it less broccoli. "Hate for it to go to waste." And then he gives Dean that pleading look, all sad eyes and downturned mouth, and seriously, he's got even the loneliest puppy in a Free To Good Home box beat.
Dean huffs something like annoyance and then spears approximately half the broccoli and two of the carrots on his fork. He stuffs it all into his mouth at once. "There, happy?" he mumbles, or at least tries to.
Sam sits back in his chair and smiles. "Totally. Now maybe try not talking with your mouth full?"
Dean flips him off across the table. "Go fuck yourself, Miss Manners."
He's not even sure where Sam gets off being so concerned, because from what Dean's heard there were a lot fewer vegetables and a lot more liquid breakfasts going on while he was in the pit. He wants to fingerpoint, he really does, but when he thinks about it it all makes sense. Sam's too busy caring about Dean-- that's why it's Dean's job to watch over Sam. It's a fucked-up system, but they're fucked-up guys and it works. Mostly. When one of them isn't dead, anyway.
So Dean pretends not to notice it when Sam is hovering like a mother hen, and he even lets him get away with the stealth-health fiber trick every now and then.
He supposes it's only fair, since he's been spiking Sam's coffee with holy water for weeks.