This was given to me as a request, I was asked to write a fanfiction based on the song 'One Blood' by Terance Jay, which, if you haven't heard, is an amazing song. I heard it and absolutely fell in love with it, there's a link to it on my profile if you would like to check it out!
Anyway, from the song this is the idea that came to me, I only heard it about an hour or two ago so this was pretty quick, I hope it's okay! Thank you so much for reading and maybe leave a review? :)

One Blood

In the far away fires, where the hills forever burn,

At the feet of our heroes, we try hard to learn,

But the lesson is lost there, in the smoke and the mud,

That we are one flesh, one breath, one life, one blood.

The battle between demons and hunters was something that had always been there. In fact, Sam and Dean Winchester couldn't recall a time in their lives when it hadn't.

It had been there for millions of years. As long as there had been demons, there had been hunters there to exorcise them, no matter how many of them were caught down in the crossfire between. It was always going to be a bitter fire, something that could never be extinguished. Hunters and demons could never live in peace, it was just something that could never work. Everybody knew it.

It was a war that would never, ever, end.

So many hunters had been slaughtered at the hands of those black eyed monsters, and so many demons had been sent screaming to hell at the hands of broken and bruised humans. Sometimes, especially lately, Sam thought that maybe it could all be considered a pointless war. There weren't any winners, only losers. Looking at the amount of hunters he had seen go down in his time, the amount of demons who had seen their own kind go down throughout their existence, he thought maybe they should have all worked that out already.

But it was a lesson that never seemed to sink in, with any of them. They all went down to the same place in the end. Everybody went to hell.

Sam had thought to himself, maybe it was time they all learned, maybe it was time to look at things and realise, no one could win. Demons smoked out of their bodies and hunters fell to their knees in the mud, but it was still death all the same.

Sometimes it seemed a case of hunters and demons being unable to live side by side on earth, and so they chose to be tortured side by side in the depths of hell instead.

But in the end, when everything else was taken away, when all the flesh was stripped back from the bones and there was nothing left but the soul within, no matter how damaged, it was all the same thing. They had all been flesh and blood at one time in their lives.

Some had just forgotten that.

I stood by the river that ran red with shame,

I stood in the killing fields where death had no name,

I stood with my brothers and awaited the flood,

And we were one flesh, one breath, one life, one blood.

Dean had never been someone to murder in cold blood, he had never been a man strong enough to kill someone without reason. Not until he had changed, when he had all but swapped armies and moved to the other side of the fight. He would look around at the bodies, the nameless and faceless people rotting around him, and he wouldn't care. He couldn't care. He was something else.

There was no empathy in the way he killed, there was no remorse and no redemption. He couldn't change that. It was who he had become.

All he could do was stand with the rest of his kind, stand with the rest of the demons that were like him, and wait. He would wait for the hunters to come for him, because he knew that they would, especially one hunter in particular, and stand to fight. He awaited their attacks, knowing how he could win so easily, and he did.

Dean Winchester always won.

The hunters knew it, the demons knew it, but no one would speak it. The demons would fear him, the hunters would still come for him, but none had taken him down. And he thought that none of them ever could.

There were two armies, one of hunters and one of demons, both led by a Winchester brother. They had the same objective, they both wanted to win, because neither could go on living with the other still above the ground. And so they would fight each other, they would send each other to hell, and it was a war that never ended.

Then I fell to the ground tasted ashes on my tongue,

Thinking that only the dead are forever young.

Everyone knew that one day it would happen, the angels had known, the demons had known, everyone except the Winchester brother's themselves had known; one day they would go down in battle. But not together. They would be the ones to destroy each other.

It was a common knowledge, shared between those with black eyes and those without. The Winchesters were to be feared. The army of demons feared Sam and the army of hunters feared Dean. There were few people strong enough to take them out, very few. But those strong enough stood and faced each other.

Things could have been different, of course they could, but they weren't.

Sam couldn't live while Dean was a demon, he couldn't live with himself. Even if it brought the end of his life, he had to stand up to the man he had worshipped his entire life. And Dean had to do the same to the man he had pretty much raised by himself.

They would never grow old, they would never move past this war, they would just die among the other soldiers who fought it. But they wouldn't die in vain.

There was peace in the twilight and for a moment or more,

It was a world without danger, a world without war,

And I would take all your suffering, it would do any good,

Cause we are one flesh, one breath, one life, one blood.

For a moment there was a state of shock throughout both armies.

Sam and Dean Winchester were dead. It was as though a silence had fallen throughout every human and every demon throughout the world, because both leaders were gone, they had taken each other out. Because they had been the only ones that could. They were the only ones strong enough to match the other. And at the end, neither came out on top. Not this time.

There was a cease of fire, a stop in the bloodshed, because things were put into perspective. All demons would ever do was kill, and all hunters would ever do was kill. They all had death waiting for them at the end of the fight, unless something happened to stop it. And that was enough to send them all into a state of utter awareness.

Sam and Dean Winchester were the ones to bring peace.

They didn't know it, they never would, but they had unknowingly gone down together.

They were still family. They were still one flesh, they had shared their last breath, they had ended their lives together, the way they always thought that they would.

The Winchester brothers would always be one blood.