Dean would as long as Sam wasn't hopped up on demon blood...if that was the case then Sam would win.....But straight up clean that would be easy Dean

If they are fighting each other, because there is no way Dean could kill Sammy, I think he's more than proven that. Now RoboSam could and would have killed Dean in a second. But if it's just Sammy/Dean I really don't think either could kill the other.

Because Dean will never kill Sammy, he will sacrifise himself for Sammy as always..
But if there was just fight just because they are mad for each other i think Dean would win..

But i think they will never kill the other.

To the death? Sam would win. He's got that kind of ruthlessness [even without demon blood or soullessness]. Dean's proven that he'd rather die himself than kill Sam. But of course Sam would need the proper motivation to do it. Like it would save the world or something. But once Sam sets his mind to something, there's no stopping him.

Yeah i agree Sam is has ruthlessness and hes a crazy fighter . An Deans always the one thats telling Sam to cool down - to relax and stuff . So maybe Sam one Day wont cool down .

Yeah they wouldn't kill each other if it was a fight cos their mad then dean would so kick ass but Dean would sacrifice himself and let sam kill him so he does not kill sam dean has proven that many times he would never kill sam

Is this a trick question? C'mon, the only way they're fighting to the death is if someone's got them under a spell or something. In which case, Dean would win. He just about did kill Sam when they were under the siren's spell, remember?

That would never happen.

It would never happen, but Sam's the one who I imagine would go through with it in the end, Dean wouldn't be able to do that to his little brother.