Prologue

It is the 45th millennium.

For more than a hundred and fifty centuries the Emperor has sat immobile on the Golden Throne of Terra. He was the master of mankind by the will of the gods, and master of a million worlds by the might of His inexhaustible armies. He was a rotting carcass writhing invisibly with power from the Dark Age of Technology. He was the Carrion Lord of the Imperium for whom a thousand souls were sacrificed every day, so that He may never truly die.

Yet even in his deathless state, the Emperor continued His eternal vigilance. Mighty battlefleets crossed the daemon-infested miasma of the warp, the only route between distant stars, their way lit by the Astronomican, the psychic manifestation of the Emperor's will. Vast armies gave battle in His name on uncounted worlds. Greatest amongst His soldiers were the Adeptus Astartes, the Space Marines, bio-engineered super-warriors. Their comrades in arms were legion: the Imperial Guard and countless planetary defence forces, the ever-vigilant Inquisition and the tech-priests of the Adeptus Mechanicus to name only a few. But for all their multitudes, they were barely enough to hold off the ever-present threat from aliens, heretics, mutants - and worse.

To be a man in such times was to be one amongst untold billions. It was to live in the cruellest and most bloody regime imaginable. The power of technology and science was forgotten, never to be re-learned. The promise of progress and understanding was lost, for in the grim dark future there was only war. There was no peace amongst the stars, only an eternity of carnage and slaughter, and the laughter of thirsting gods.

As the light of the Astronomican declined, Black Crusades and millions of xenos took advantage of humanity's weakness, fighting for the ruins of the fallen empire. In the end, the Holy World of Terra and the Golden Throne themselves were under siege. But the heretics, mutants, demons and xenos did not savour their approaching triumph for very long. The Great Devourer was here, and the galaxy fell to its unlimited appetite. Divided and sworn to selfish masters, the races of the Galaxy fell against the ultimate predators.

Hope died, and the galaxy was scourged of life. Yet in the final hours preceding the final defeat, a last gambit was attempted.

And the course of history would never be the same again.

The noise was infernal. Thousands of corrupted tanks of the Black Legion had opened fire at the same time, deafening any human or xenos stupid enough not to have thought to shield their ears. Hundreds of thousands tons-weighing batteries followed the movement, snipers adjusted their targets with faster-than-light rounds. Shells fell upon the charred battlefield, leaving large craters.

It was a scene of apocalypse. The sky was covered in ashes. Spores and detritus landed in a nefarious rain, poisoning and corrupting the ground, causing more horrors to spawn from the earth. Corrupted Dreadnoughts unleashed their fury, pouring hundreds of heavy bolter rounds in seconds, recharging and then unleashing more. Large blasts of liquid promethium carbonised the living and the dead, the flamethrowers repeating their sinister task as fast as they could.

Like an implacable juggernaut, a lone Reaver Titan towered over the battlefield, crushing every ally and enemy who had the bad luck to meet its path. Weapons of unimaginable power flashed, dispensing death to entire sections of the plain in an instant. Valkyries fought in the sky with missiles, drowning their opponents in plasma when they came into close range. Reality sundered as daemonic legions emerged from the Warp and tore up the frontiers of the material realm. Berserkers of Khorne charged in the murderous manner the servants of the Blood God were so renowned for. Horrors in service of Tzeentch invented and tested mind-bending sorceries on the fly, modifying physics and the laws of nature to shatter flesh into gory fragments. Viruses and diseases so lethal they were able to destroy entire star systems were brought to the frontlines by the Nurgle worshippers. Waves of unbearable emotions and tortures were deployed by Slaanesh's fanatical and drugged slaves. The Warp itself roared in fury, destroying reality in several places, bringing hordes of demons avid of more carnage.

And despite this, the enemy kept coming like there was no tomorrow. The swarm of the Tyranids had lost millions if not tens of millions of organisms since the start of the assault, but with a relentless energy no sane commander could have ordered, the assault continued, soaking casualties like a dark wave, erasing traps by sending uncountable expendable members of the swarm to their deaths. The simple warriors of the brood had attacked first, and were now filling in eight out of ten trenches with their corpses.

In the middle of this insane melee were the Astartes. Clad in their midnight battle armours, the Chaos Marines were a hurricane of destruction. Brandishing chainsaws, powered claws and swords fuelled with the most ignoble of sorceries, the legionaries ripped Genestealers, Termagant and Hormagaunts by the dozens with the help of their demonic weapons. The Tyranid Shrikes were pulverised by the thousands, the Gargoyles were annihilated, more macabre remains dispersing into the atmosphere.

"FOR ABADDON! FOR THE BLACK LEGION! FOR ARGGGHH..."

A legionary in the middle of a battlecry was literally skewered by a large blade come from nowhere. The chameleon-version of the Lictor had not the time to do more, as the Black legionary next to his unfortunate comrade seized this chance and torched the monstrosity in one long session of fiery agony.

"UNDERGROUND! THEY ARE UNDERGROUND!"

The ranks of the Astartes momentarily stepped back, before planting with Warp sorcery more mines under their very feet. The others kept firing, vanishing the ranks of the Tyranids that tried to storm the redoubt.

"FOR THE WARMASTER! KILL THEM ALL!"

Deformed bolters and daemon-possessed weapons shot a torrent of pure death, ravaging close to three hundred tyranids. Two corrupted tanks which had remained silent until then added their fire to the ongoing massacre, stacking the piles of Tyranid corpses seven metres high. Then more incendiaries and spells were thrown away, creating a true wall of fire that should give the Black Legion half a minute to rest before the next assault on the fortified position.

Sorcerer Urus the Ingenious watched all of this from the heart of the bunker, buried kilometres under the surface where the clash of demons and Tyranids embraced everything. His long-range sorcery had remained surprisingly reliable so far to see what the enemy was planning, in spite of the Tyranids casting their much redoubted shadow in the Great Ocean. Now, if only the Black Legion had the forces to do something about it...

"The Carnifexes are coming."

"How many?" Asked the warlord of the Black Legion he had sworn his sorcery and his skills to, Gavar the Murderer of Billions.

"Tens of thousands."

The answer of the Black Legion warband leader was a long series of curses, some that Urus would have sworn to Tzeentch in person he had never heard them before.

"So this is how it ends." There was no despair, just a simple assessment. "Our fleet, destroyed. Our armies, defeated. We are all going to become bio-mass for the Great Devourer."

"It is not like we had the army to destroy Hive Fleet Sidious by ourselves."

Proof that Gavar had long arrived to the same conclusion as Urus, the Black commander simply nodded, a move which made his skull-shaped helmet even more terrifying. Urus could not help but feel hints of relief and regret. Relief that Gavar was not going to grab him by the head and see if a former Thousands Sons legionary could survive without this appendage. Regret because when a bloody warmonger like the Murderer of Billions stayed away from the battlefield, it was really best not to be on the frontlines.

"At least we cost the Hive Mind a lot of their bio-mass and transports."

The battleship and the three cruisers had made sure of that in their death, and there were denizens of the warp still fighting in the debris of the orbital stations.

"For all the good it will do." grumbled Gavar. "They are covering the entire Galaxy. What a way to end the 45th millennium!"

Hive Fleet Sidious was an aberration of nature by itself. When compared to the size of the first Tyranid Hive Fleets detected, fought and vanquished in the 41st Millennium by the False Emperor's lackeys or the xenos, Hive Fleet Sidious was ten times the size of Behemoth, Kraken and Leviathan. Combined.

It was already bad, but the fact that three other Hive Fleets of the same size if not bigger were attacking at the same time the galaxy made things outright desperate. The Black Legion, which had been on the verge of victory over the decrepit Imperium after the 48th Black Crusade, had been unable to withstand the assault.

Ultramar, conquered after annihilating nine out of ten Ultramarines, had been razed by the Great Devourer and its cohort of hungry slaves. Deliverance, Bakka, Ichar IV, Moloch, Baal, Solstice, Galen, Vanaheim, Molov, Valhalla, Tallarn. It had cost the Black Legion millions of souls to devastate and occupy these worlds, only to lose them in a matter of weeks when the Hive Tyrants debarked.

The warband of Gavar the Murderer of Billions had, under the orders of the Warmaster himself, rushed to the Hive World of Neptunio Quintus to slow or at least slightly delay the Tyranids ravaging thousands of worlds. It was no shame to admit the Great Company assigned to this task had utterly failed. The fleet had preceded the Tyranids by mere hours, leaving little time to build up major defences when the servitors of the Great Devourer darkened the skies with their spores and astronomical numbers. Preparations and cultists adequate to defeat an ork warband or a tenacious xenos enemy were totally worthless in slowing down a full Hive Fleet.

"Now, Urus, tell me you have a plan."

"My lord, I am unsure of what you want me to do. I can't open a Warp portal to escape-"

"I don't want to escape sorcerer! I want-"the gaze of Gavar turned dangerous. "I want to crush them! I want to rip out their souls, see the light fade in the eyes of the Hive Mind!"

Urus took a step back. Warlord or not, what his lord asked was completely impossible.

"My lord, you don't need an army or a miracle. What you need, assuming it existed, would be a couple of hundred Primarchs-Daemons and several thousand Bloodthirsters. Oh, and three hundred battleships."

At least, Urus didn't add. To defeat Hive Fleet Sidious. The defeat of the others Hive Fleets would require more resources, more warships, more Titanic Legions, more Astartes. It would require worlds with daemon help and huge depths of manpower to produce ammunition and fuel.

"Isn't it a bit pessimistic, Ingenious One?"

Urus felt something really unpleasant pass over his skin. The voice of Gavar wasn't the same anymore, his eyes were now a flashing blue and the aura surrounding his Mark VII-corrupted armour was showing clear signs of Warp possession. Summoning all his will to not be broken by the intensity of the Great Ocean coming, the sorcerer answered.

"No. It's not."

"The Architect of Change, as it happens, agrees with you."

That, Urus had not expected. Of course, given that it was certainly a daemon of Tzeentch reputed for the quality of his lies in front of him, a certain prudence was needed.

"What is the will of the Architect?"

"A ritual. The Great Changer requires a ritual."

"To do what exactly? Tear the planet in half? I think no ritual is needed for that. Give the Tyranids one hour, and the Great Devourer will have taken care of this world."

"Don't make yourself sound more stupid than you already are, Dumb Sorcerer," retorted the demon with the distorted voice of Gavar. "Lord Tzeentch has no need to do a ritual for that."

"Why me? Why not Ahriman or the other senior Corvidae Sorcerers?"

"They are no longer in the material realm," the daemon admitted with a shrug. "You are."

The Black Legionary shivered at this implication. Ahriman of the Thousands Sons had been widely acknowledged as the most powerful Astartes sorcerer to have ever wandered the galaxy. To hear of his death was...disconcerting.

"Is it that bad?"

"Depends. Do you consider the Despoiler dead and the Tyranids before the Eternity Gate of Terra bad?"

No, that was not bad. That was apocalyptically disastrous.

"The last battle between the Great Devourer and Chaos is about to begin." It was not a question.

"Indeed. Now gathers your servants. They have a final role to play in this story."

Half an hour later saw Urus outside a bloody eight-pointed star of Chaos. The blood was that of his servants, who had given their lives on the order of their master to fuel the ongoing ritual. As far the sorcerer could tell, the process was going fine. For the moment. No one could be absolutely sure after all, with the daemons and the mysteries of the immaterium. A ray of murky violet light was illuminating the room of the bunker where the Great Ocean was pouring. A hurricane of power, fuelled by eighty-eight sacrifices and maintained by the will of an Astartes doted from psyker powers.

Nevertheless, the explanations of the demon having taken possession of Gavar body had been relatively straightforward. Emphasis on the relatively. It was a servant of Tzeentch after all. According to the child of the Warp, the goal of this incantation was to cross the barrier between dimensions and grab a Champion which would have the power to stop the multitude of Tyranids, place him under the aegis of the Chaos Gods. Then send this prodigious being into the past, to a point in time where their influence would allow the Galaxy to prepare for the endless hordes.

It was complicated. The horrible mathematics hurt the former Thousands Sons' eyes. Urus felt no shame to admit the exact specifics of this sorcery were far, far out of his league.

"Now!" snarled the body of the warlord, with mannerisms reminding all observers that the mind of the Astartes was definitely no longer available to command the flesh. "The Great Plan is going to be achieved! Execute the Weaver Option!"

"By your command," answered Urus. Disobeying would have meant his instant demise plus a long eternity of torment for his soul in the empyrean, and it would have been for naught. The Tyranids had extinguished the better part of the Black Legion and were now digging for the bunker, no doubt having an idea who their next meal was.

Activating the first spell in a whirlwind of blue and green with his hands, the Black sorcerer slowly started to pronounce a dark incantation in words hurting the very fabric of reality. Second by second, a dome of sorcery formed around the black vortex.

"Is the ritual proceeding to your expectations?" The sorcerer was straining under the effort, and, despite his attempt to hide it, he was well aware how tired and strained his voice sounded.

"The power is-"

Gavar - or rather, the being speaking through Gavar's mouth - had not the time to finish the sentence. His head and the majority of his torso disintegrated in a red mist. Surprised, the Black Legionary managed to stabilise the spell in a miraculous feat of mental control. It didn't last.

One second later, it was the turn of Urus' right hand to vaporise itself, ending all possibility to harness the raw strength of the Great Ocean. The dome of sorcery began to vanish, with the vortex becoming unstable. From within this black and indigo colours merging in a torrent of energy, the Black sorcerer saw his end.

Struggling against the pain, Urus turned his head towards the shadows from where the shots had come. Out of it, emerged a Space Marine wearing the hated blue armour, gold aquila and infamous white omega symbol.

"An Ultramarine...I thought the Warmaster had killed you to the last."

"You thought wrong." It was difficult to miss the satisfaction in the voice of the Corpse-God's follower.

"Have you any idea what you have done Son of Ultramar? This ritual could have saved humanity and the galaxy."

"You are wrong traitor." The tone employed by the descendant of Guilliman could have frozen a warm planet. "Nothing your kind of traitors can do will ever save humanity. The Inquisition knew of the ritual the demon had in mind. Triumph of Chaos was the achievement sought, not saving the galaxy."

"And what are you going to do?" Urus laughed bitterly, feeling the severity of his wounds worsen by the second. "Try your own ritual?"

"It's already done." Replied the Ultramarine tranquilly. "The Champion you selected has arrived in this universe and was sent in the past."

"You expedited the ritual before we could attune his essence to chaos." Terrible understanding filled Urus' mind. This changed everything. This was disastrous. This was-

The bolter, a magnificent work of ceramite and plasteel graved in gold and platinum, pointed directly towards his head. The Astartes sworn to Tzeentch looked into the eyes of his opponent and saw no justice or mercy. Just pure, unrestrained revenge and determination. The blue-armoured Space Marine understood what destabilising the ritual meant for him...and had accepted it.

"Farewell, Traitor."

For only the third time in his long life, Urus the Ingenious of the Black Legion, once a proud Son of Magnus and loyal brother in arms of the Thousand Sons, felt true despair. The Warp distorted and broke apart the rift between dimensions, out of his reach and out of control. It did not require a great deal of reflexion to understand that no matter his personal fate, the outcome was not going to be the one Tzeentch had wished for. Or maybe it was?

The sorcerer closed his eyes. The energies of the empyrean flooding the chamber. The sound of the bolter firing. Before everything went dark, a millennia-old battlecry reach his ears.

"FOR THE EMPEROR!"

Author's note: Thanks to Thanathos my beta paladin, this prologue is at last properly beta-ed. The Emperor must have filled him with His Determination, because he has accepted to do it for every chapter of the Arrival, Peril, and Sentinel arcs, in addition to his monthly duties.

So from April 28 onwards, I will try to regularly update here the beta chapters of the Weaver Option. It will not be fast, the story has to continue and I'm not a magician, but it will be done.

Thanks for all the readers supporting this story.

Other interesting links for the Weaver Option:

P a treon: ww w. p a treon Antony444

Alternate History page: www .alternatehistory forum/ threads/ the-weaver-option-a-warhammer-40000-crossover.395904/

TV Tropes: tvtropes pmwiki/ / FanFic/ TheWeaverOption