Author's Note: This is the prologue and set-up for my Warhammer 40k/Halo fusion fic. I hope you all enjoy it.


The Elder One screamed.

It was a silent scream, at least to the ears of all who dwelled in the galaxy. And even if it was an audible scream, not even the scream of a supreme being could possibly be heard over the collective cries of pain of a universe consumed by agony and death. Death. Death was everywhere, and after so many eons it had driven the Elder One mad.

Across the galaxy the total loss of life was incalculable. The race that was humanity had formed an empire that went across the stars, but they were cruel and callous to all other forms of life, and in their constant wars and battles they spent lives more than they did the ammunition in their guns. Every day they sacrificed millions to sustain the corpse they called their "Emperor". The Eldar, the chosen of the Elder One and the pantheon now all but completely wiped out had been reduced to a dying race that was always struggling to survive, more than comfortable with condemning the rest of the universe to a fiery death if it meant saving themselves, or alternatively dragging everyone down with them if survival was not possible. Many others had willingly become full-blown monsters, obsessed with torture and with pain in the service of nothing but their own sadism.

And then there were the other races, none of whom were any better. Orks, green-skinned barbarians and savages, surged through the galaxy destroying everything in their path simply because they had not the intelligence to do anything else. On the eastern fringes of the universe, a seemingly unstoppable race known as the Tyranids were devouring entire worlds and nothing the Eldar or any of the other races did could halt their advance. From the darkened caverns beneath seemingly abandoned worlds, legions of unkillable mechanical skeletons marched to war alongside their floating monoliths, constantly harvesting more and more souls in the name of their masters the C'tan, monsters that had been the Elder One's greatest failure. Surging through the galaxy assimilating and killing anyone in their path was the Tau Empire, a coalition of races that committed atrocities in the name of a supposed "Greater Good".

And yet all of this paled in comparison to the depravations of the Four Powers. A quartet of Demons from another dimension, these abominations were omnipotent and omnipresent in equal measure, having spread their wicked influence to the whole of the universe and corrupted billions. Even worse, they drew power from the positive things in the universe as well as the negative. In this way they could not be stopped, nor could the monstrosities that served them or the black-armored titans that killed millions in their name.

In short, the Elder One's world was the very definition of hell, and he was cursed to be in it and experience its suffering until one of the many factions inevitably wiped out all the others.

But amidst the monotony of agony and misery and death, the Elder One's other senses took notice of something he had never taken notice of before. It was subtle at first, and he did not sense it amidst all of the usual agony he suffered. But then, like training one's ears to focus more on a curious whisper, the Elder One willed himself to focus his all-seeing senses on that which he had detected against all odds. He willed himself to see through the storm of blood, to push past the endless horrors of never-ending war. And then, finally, after what was decades to everyone else but much less to the Elder One, he finally saw what he was looking for in full.

And he saw another world.

Not another world as in a planet, rather, this was another world as in an entirely different universe. One bereft of Eldar, Daemons, Orks, and the other races of the Elder One's universe. All that is except for one: Humans. Humans existed in this world and like the ones in the Elder One's universe were fighting for their very existence against aliens who wanted to wipe them all out.

How strange... The Elder One thought. That this one race existed in this other universe when none of the others did. In their place where other species, races that all seemed to want humanity dead. And as the Elder One looked on he could see that they were being mostly successful in this goal of genocide. Humans died in droves against these other races, but nevertheless fought tooth and nail against them. And as the Elder One continued to stare into this other universe, he realized that there was something here that simply did not exist in his universe:


The fact of the matter was that no matter how many times these other races slaughtered them, no matter how far back the humans in this universe were pushed, they continued to fight, even when on their hands and knees bleeding. They fought, and as the Elder One realized, they continued to fight against insurmountable odds for two reasons: one because there was still a chance, however slim, that they might just win, and the other reason was because they were fighting not just for their continued existence, but for their future.

In the Elder One's universe there was none of that. In place of hope there was nihilism. Humans still fought without quarter against other races, but they had no future in victory that they could never attain. Only more violence and death, and the same was true of all the other races. None had any future or hope whatsoever. They all continued to fight simply because it was all any of them knew, and would continue to do so until one of the races finally managed to overwhelm and destroy all the others.

It was in this moment that the Elder One realized what he had to do. What he had to do to free himself and his universe from the never-ending nightmare both were stuck in.

Reaching out to this other world as much as he could, the Elder One called on what power he had left and willed himself to do the impossible: he would fuse his world with the other one. He would create something entirely new from two separate things. Create a greater whole that had the best of both worlds. It would have the life of his world without the nihilism. In its place would be the hope and uncertainty that the other universe had. For even if it would all be in vain, and even if there would still be misery, war, and death, it would still be vastly preferable to what he lived in now. Anything was preferable to what he lived in now. So it was that he willed himself, called on all of the power he possessed, and then finally, acted, before the Four Powers, C'tan, or surviving Eldar Gods could realize what was happening in time.

And then there was a bright, blinding flash, and in an instant, all of the fighting, violence, and death in the Elder One's universe ceased. Not a single living (or unliving) soul in his universe was spared from the great fusion he brought about. The other world was drawn into his, mixed and merged until finally, when he was certain that he had done what he could and also when he felt his power begin to wane, the Elder One ceased, and the bright light vanished from the cosmos.

And with this action, one new, single universe was created.

852 BCE
T'vin Korons had been fighting for and serving the Sangheili Empire for decades, and during his service, he had helped to bring many scattered Sangheili tribes into the empire, determined to spread the truth of the Empire's ways to them all. Finally, after centuries upon centuries of fighting and assimilation, the Sangheili Empire's attempts at completely and totally unifying the Sangheili race under one banner were on the cusp of success.

And then they had come.

Appearing out of the sky in a massive space-station, the race of physically frail beings known as the San 'Shyuum had made clear to the Sangheili that they were on their planet looking for relics left behind by the Sangheili's Gods the Forerunners. But for the Sangheili, tampering with their g-ds technology in any way was heresy, and as neither group was remotely willing to compromise, war had broken out. On the ground it wasn't even a contest. The San 'Shyuum were so pathetically weak that T'vin for one felt guilty butchering them in droves. In space though it was different. While the Sangheili were capable in the air to a degree, they had nothing that came close to matching the power of the San 'Shyuum's dreadnought. Thus began a stalemate that lasted for almost nine decades before at long last, a truce was reached and the two sides agreed to sign a treaty known as the Writ of Union, which would form a holy alliance that from that day onward would be known as the Covenant.

Only, while the Covenant was formed and it changed the Sangheili forever, the Writ of Union was never signed.

Instead when the Sangheili sent their emissaries to the San 'Shyuum's dreadnought to sign the Writ of Union, they found that every single San 'Shyuum on the station was dead. Not one had been spared. Their killers were a varied and vibrant lot who said that they had saved the Sangheili from enslavement to weaklings and that they could offer them power beyond their wildest dreams, along with anything else they could ever want. All they had to do was pledge themselves to them. Considering that whatever these things were they had single-handedly wiped out a race without batting an eye, even it was as pathetic a race as the San 'Shyuum, the Sangheili decided to hear these strange beings out.

They called themselves the Daemons of Chaos, and their leaders were four omnipotent beings known as Nurgle, Khorne, Slaanesh, and Tzeentch. Each of them stood for something different, and each of them offered different promises to the Sangheili race. Most of the Sangheili, T'vin included, were extremely wary of these so-called "Four Powers" who offered everything their race could want with loyalty as the only price to be paid. To most Sangheili, it was too good to be true.

And yet for all of that when the Sangheili emissaries returned to their planet's surface, not only had they agreed to sign on with the Daemons on their whole race's behalf, they themselves had already pledged themselves to different Daemon Lords, with each of the Four Powers now having its first of many Sangheili servants. Because the emissaries had signed the contract and the race was under one empire, most Sangheili accepted their new alliance with the Four Powers and their creations without resistance and one by one, all Sangheili pledged themselves to a different one of the Four Powers. What precious few Sangheili objected to the decision to accept the Four Powers did not last long. In less than a year, every single Sangheili on the planet was pledged to a different Daemon Lord.

And so it was that the Covenant was born, and the whole galaxy would suffer for it.

Author's Note: OK, now that the prologue is complete I gotta make a few things clear so no one gets the wrong idea as this crossover continues:

1. First off, I am well aware that there is no "Elder One" in the Warhammer Universe, but I wanted a supreme being to fuse the two worlds into one, and this seemed like the best way to do it. The Emperor of Mankind is powerful and all, but he's not really in a position to do something like this, and even if he was, I don't think he'd necessarily object to the humans are jerks part, considering he himself defines that.

2. Word of warning for hardcore Warhammer 40k fans: I am only a casual fan, so if I get anything wrong, I apologize in advance. And I know for a fact there are some things in my crossover that will be different than the actual continuity, particularly with the Four Powers and Chaos Space Marines. These are my interpretations for the purposes of the crossover, so some things will be different.

3. Don't expect any X-rated violence. While there will definitely be lots and lots of fighting, I'm not going to, shall we say, go into detailed descriptions of heads and bodies exploding and stuff like that.