Disclaimer: I own neither My Little Pony: Friendship is Magic nor Warhammer 40000.
This is written solely for the purpose of enjoyment, with no monetary gain.
Prologue
The Lux Foedis screamed.
Caught in the relentless currents of the powerful warp storm, the ship was being slowly torn apart. Currents of aetheric energy slammed into the weakening Gellar fields, twisting the ship uncontrollably as it tumbled through the screaming madness of the Immaterium. Vast daemonic talons raked her sides, clawing at the bubble of enforced reality that surrounded and protected her, scenting the delectable souls of her crew. Her mighty keel twisted, emitting a horrible metallic screech like a creature in its final moments of mortal agony.
Inside her hull, tech-priests struggled frantically to bolster the ship's dying machine spirit. The Lord-Captain bellowed orders to the bridge crew, as the Navigator peered desperately into the Warp, seeking the light of the Astronomicon that she'd lost sight of hours before. The effort proved fruitless, so instead she sought out any fleeting islands of stability, seeking to prolong the ship's life in the vain hope that the storm would blow out. She knew there was every chance that she was guiding them deeper and deeper into the seething hell of the Warp, but no other choice presented itself.
It was in one of those fleeting instants of calm that her pineal eye saw something like, yet unlike, the Astronomicon's beacon, illuminating what might possibly be a safe harbor, a sheltering island of reality. She seized upon it like a drowning woman bumping a piece of driftwood.
At the Navigator's instruction, precious power that the tech-priests had hoarded like misers flowed into the warp engines, violently sundering the veil between real and unreal. The cruiser Lux Foedis, once-proud vessel of the Rogue Trader Parseon Anderocus, staggered drunkenly through the rift, streamers of vile psychic energy cascading down her sides.
Her once-mighty engines flickered, barely supplying enough energy to nudge her into orbit around the gleaming gem of the world below.
Behind her, daemons howled in inchoate rage, seeing their prey escaping. Bursts of foul warp energy blasted forth from the Warp rift, striving to hold it open, to tear it wider, and in the process the rift bathed the world below in screams of hate and unclean lust.
Chapter One
Twilight Sparkle leaned forward where she lay on her balcony and peered through the eyepiece of her telescope, carefully adjusting the focus knobs with her telekinesis. She made a small sound of satisfaction as she located the comet she'd been tracking for the past few nights. Right where it's supposed to be, she thought, a soft violet glow lifting her quill pen so she could begin recording tonight's observations. The comet wasn't terribly close yet, but her calculations suggested it would be a spectacular feature of the night sky in a few weeks' time.
She quickly jotted down precise astronomical references on the scroll next to her. Twilight was only an amateur astronomer, but she took her hobby seriously, and within minutes she'd filled about half the scroll with detailed notes of the comet's brightness, color, and position in the sky with respect to both the nearest cataloged stars and the nearest major beacon stars. She double-checked her notes with a critical eye, made a few minor corrections, and gave a satisfied nod. Placing her quill to the side and capping her inkwell, the lavender unicorn softly called out to Owloysius. Her nocturnal assistant came flying out to the balcony on silent wings, alighting on the railing and regarding her with his huge eyes.
"Who?"
"Would you mind storing this with the rest of my astronomy notes, please?" Twilight levitated the scroll up to the little owl, who reached out and gripped it in his talon.
"Who!" Owloysius launched himself back off the railing, doing a quick circle around Twilight's head before heading back into the library as silently as before. The unicorn laughed quietly at his antics, trying to keep her voice down in consideration of the sleeping Spike, even though she knew it would take one of Pinkie Pie's parties rampaging through his bedroom to wake the little dragon; he was a heavy sleeper.
A party rather like the one that was going on now. Twilight idly crossed her forelegs as she looked over the rooftops of Ponyville to the lights shining at Sweet Apple Acres. She could just barely hear the music, the sound carrying far in the cool night air. Today marked the last day of summer and the beginning of fall, a holiday known as Cooldown. This year, the Apple family was hosting the celebration, and Applejack had gotten together with Pinkie to organize and plan the party. The two earth ponies had been working to prepare this celebration for over a week, and it sounded like it was going well. Twilight had felt a little bad when she told them she wasn't going to be able to make it, explaining that she'd found a new comet and that the first few days observations were really, really important. She'd apologized profusely, hoping she wasn't hurting her friends' feelings. Pinkie hadn't been upset though, to Twilight's relief, asking if the academic would be free the next week, and offering to set up a smaller, belated celebration with just her closest friends to make up for the party she was going to miss. Applejack hadn't been upset either, taking the news of Twilight's absence with the same equanimity that the farmpony greeted nearly everything with.
Twilight had accepted the invitation to the later party, touched by the pink pony's thoughtfulness. She wasn't the only one that would be missing tonight's party, either; Rarity had had a huge order come in from Hoity Toity's boutique in Canterlot for new fall clothes, and she'd fallen a bit behind. The designer was having to work feverishly to meet her deadline; the shipment had to go out first thing in the morning, and she'd still had a lot to do.
I could probably still make it to the party, Twilight mused. I've gotten all of my observations done, and it's clearly still going on. There are probably a couple of hours left before it breaks up. While Rarity wouldn't be there, the rest of her friends almost certainly would. Pinkie and Applejack were hosting, Rainbow Dash would never miss anything with "cool" in its name, and Fluttershy… would probably be there because everypony else was, though she'd probably be trying to blend into the walls of the barn. Well, maybe not by now; the yellow pegasus did have fun at parties, but usually only after she'd been there for a while and had time to relax.
Still, Twilight found herself enjoying the momentary quiet and solitude. She'd never trade her friends for anything, but she did occasionally enjoy having time to herself. She lay on her balcony, legs tucked comfortably underneath her, and just gazed up at the sky, drinking in the calm beauty of the thousands of tiny, twinkling lights and the huge, silver full moon.
Something odd in the starfield glittered in the corner of her eye, and she turned to look at it. Twilight frowned; she'd never seen this light before, and it was more than bright enough to be quite noticeable. Her horn glowed as she started to bring her telescope around, but she stopped before finishing the motion.
The light pulsed and flared, emitting an odd, purple-white glow that should have been pretty but somehow really, really wasn't, and Twilight had the sudden feeling that she didn't want to look at it more closely.
She frowned more deeply. Where had that thought come from? The lavender unicorn was intensely curious by nature; not wanting to look at something new was totally alien to her normal way of thinking. Brushing the odd moment aside, Twilight rose to her hooves, moving the telescope so she could get a better look when…
*rage*
The feeling slammed into her with the force of a plummeting sky carriage. She shook her head, trying to regain her equilibrium, wondering where…
*fear*
Twilight stumbled, violet eyes wide as another wave of emotion smashed into her. She realized that these emotions weren't hers, they were…
*lust*
They were coming from somewhere else! Were they being projected? Who would do that? Twilight scrambled to strengthen her mind…
*hate*
Something was attacking her! Twilight's horn glowed anew as she slammed together wall after mental wall, forming her mind into a bulwark against the intruding emotions. They continued to wash over her, digging at her mental barriers with phantasmal talons, but she held firm, and she could swear something recoiled from her with a thin scream, but there was nothing there.
She tried to identify the hostile emotions without allowing them to touch her. They were all negative, many grotesquely so. She felt grimy, like the intangible feelings were leaving physical trails of filth across her coat as they passed.
Finally, the waves began to abate, and she shuddered in relief, unsteady legs dropping her on her haunches. She ran a quick mental inventory of herself, and as far as she could tell, she was unharmed save for that lingering unclean feeling. Even that was beginning to fade. She looked up into the sky again; that oddly ugly light was still there, but it was much dimmer than it had been moments ago.
She sighed, relaxing a bit as the sudden threat abated.
That was when she noticed the screams.
Elsewhere
Urgency. "Sister, Awaken!"
Concern. "Yes, what is it?"
Further urgency. "The Veil, Sister, it is torn! There has been an incursion!"
Confusion. "I sense it! How many?"
Anguish. "Dozens, perhaps as many as a hundred. I tried to seal it, to hold Them back, but… I am not yet as I once was! I am still diminished, and the Four have the scent of Our world again. They are fighting Me, trying to force the breach open wider!"
Reassurance. "I lend My strength to Yours, Sister. Hold fast, We can repair this. It will take time, though. How did this happen?"
Uncertainty. "A ship, Sister. It made the breach, and it sits in the sky now, in Our domain. It is a ship of His people, Sister."
Worry. "His people? Truly? We have not heard from Him in an age. I fear the worst."
Stronger worry. "As do I, Sister. I know You feared the sons He made…"
Correction. "I did not fear them. The way He used the information on the Elements You shared with Him… disturbed Me, yes. He inverted their power, combined them with other sorceries and turned them against the material, not the Immaterium. He made them to stand alone, when they were always, always meant to stand together. I worry that the resulting beings were terribly, terribly flawed."
Defiance. "He needed tools to unite His people. He wished to carry the fight to Them. Imagine, Sister, a universe free of Them! His ambition was a worthy one!"
Sadness. "Fighting Them only strengthens Them. They can be resisted, but should never be directly fought; it is better to starve Them than it is to fight Them. I know You disagree with Me on this, Sister…"
Regret. "Yes. And that disagreement, in part, gave Them inroads into My heart. It… may be that He was wrong, that I was wrong, but I still do not believe so. I wish I could ask Him… These are His people. Perhaps they could tell Us what happened to Him."
Sternness. "Nothing good, I fear. And these are but mortals; He has been silent for long, long ages. They will not know Him."
Bleak Hope. "They may. Legends, stories, a hint here or there, anything would be better than the nothing I have now. I know You were wary of Him, but He was My friend, Sister. I miss Him so."
Sadness. "I know You do, Sister. That sorrow and loneliness, more than Our disagreement, gave Them a hold upon You. We will ask them, but We should not speak to them directly, or We might harm them. Let Our people speak to them. We both would rather not see them harmed."
Cautious hope. "Would You volunteer Your protégé?"
Affirmation. "She would be My first choice, yes, though I suspect she may not thank Me for it. Now, We must focus Our energies toward strengthening the Veil. We cannot repair it immediately, but We can patch it, hold Them back long enough to deal with this incursion, and prepare Our people to speak with His. Then We can bend Ourselves toward restoring the Veil. It will be an arduous task, throwing Our might against the Four once again. It has been a long time since we last had to face Them."
Gratitude. "Thank You, Sister. Once the patch is set, I will go to Your protégé, to tell her what she needs to know. You, I think, would be better suited to deal with the incursion. It seems largely confined to those large cities that are far from Us. I believe the villages are safe."
Affection. "Yes, Sister, I believe that would be best. I believe You will enjoy My protégé; she is curious like You, though less fierce. Perhaps she can learn from His people what happened to Him."
Creeping fear. "I only hope… I hope with all My heart that that scream, that constant, eternal scream that We have heard every moment of every day for ten thousand years… is not Him."
Dread. "I hope that too, Sister. I hope that, too."
A brief note on scale: For the purposes of this story, I'm assuming that the median size for Equus Sapiens subspecies is Equus Sapiens unicorns, at about 3'6" (~107 centimeters) with E. Sapiens terrene a bit larger and E. Sapiens pegasus a bit smaller. E. Sapiens deus is obviously much larger, but that's neither here nor there.