Original prompt:
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>you and twilight will never conquer the universe

>You were there when the map called Twilight and all her friends to Canterlot.
>You've seen Twilight through her worst, as Celestia finally went mad and other princesses failed to subdue Daybreaker.
>Twilight's hesitation to deal with her mentor using Rainbow Power ended up costing her everything.
>Covering her escape, Cadence and Luna tasked her with evacuation.
>She only managed to teleport her friends and you to safety before Canterlot and everything around it became a scorched hellscape.
>You were there for her when she pushed you away in despair, you were there to comfort her when she didn't want it, blaming herself for everything.
>You were there to see her growing bitter and resentful towards herself.
>She overcame even this, together with you. She needed you to be there for her.
>But she didn't take you with her for her return to Canterlot with her friends to put an end to Daybreaker's carnage.
>You never knew what happened. You only saw the sun finally going down. And then she came back alone.
>Burnt. Broken. Manic. Horn crackling with alicorn magic. Eyes clouded by unfamiliar power.
>She asked if you will be with her still. You would never betray her.
>You saw her taking control of what's left of Equestria all alone, only you by her side.
>Back then you've promised you will stay with her no matter what.
>Now, standing at the right side of Empress Twilight's throne, you are still as resolute as ever.
>Ponies from different worlds you've conquered who came to see her today know you only as her knight.
>Granted with power beyond space and time by your lady, you've vanquished everyone in your path as her wings painted the skies above you with starry gloom.
>In Twilight's Kingdom no one shall suffer what her world has suffered. No room for mistake is made under one banner of cosmic twilight, spanning the whole Universe and beyond.
>In her hooves everyone is safe.
>Just like even after centuries of conquest it's only in your arms she is safe.

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>In the grim dark future there is only friendship.
>A special kind of friendship your Lady offers to those in need.
>Reaching through time and space, she extends her hoof in promises of safety, support and defense.
>There's just a simple trade to be made first.
>And so here you are, extending your own hand in a friendly gesture to trembling princess Twilight who tries to cover Anonymous from a possible attack with her body and wings.
>Of course you have no reason to attack. There is nothing to provoke you. Your armor can't be penetrated by any kind of magic.
>Your sword is more of a symbol than a weapon. A symbol of conquest and subjugation of all the worlds you've claimed in your Lady's name.
>This one had no idea what's coming and was easy to conquer.
>The last line of its defense was right in front of you.
>"Get away from us, you monster! We have nothing more to give to you! Haven't you done enough?"
>Despair seeps through the cracks of Twilight's angry voice while Anon was just silent this whole time, probably realizing all too late how useless he is to his mare in her time of need.
>Something you both shared once, but no more.
"You know perfectly well what I'm after. I won't harm you if you give it to me like the other princesses."
>"Will you let us go if I do? Promise me. Swear on her name!"
>Closing your eyes you envision your Lady in all her glory.
"In the name of Empress Twilight I swear, no harm will come to you and your people if you give up all your magic."
>She doesn't really have a choice but that wasn't the point.
>Anon meekly calls his Twilight who just sighs in defeat, not hearing his plea.
>Her horn lights up and you feel powerful magic escaping through it, caught right into your faithful blade.
>Enchanted metal lights up with her colors, bathing in her essence. Cutting what can't be cut, severing the bond that should never be severed.
>It is only in your right to do that.

>The deed is done and Twilight collapses in Anon's arms, her rump now bare purple as the rest of her body.
>The princess is no more. A crude, lowly body with no magic, no special talent and no purpose.
>Her human looks at her and shakes his head.
>"I can't believe you're doing this. Why? Aren't we supposed to be similar?"
"Maybe we are. Just as much as your Twilight is similar to mine."
>Anon ponders this for a moment but the expression of helplessness never leaves his face.
"Give her some time to rest. She is going to be fine. Your Equestria is safe now."
>"Safe?!"
>Venom in Anon's voice can't poison your mind, over the years you've become immune to all the bitterness surrounding your work.
>"Look around you! Canterlot is razed, ponies are scared, princesses' magic is gone... W-who will even bring the sun up anymore?"
"We will."
>Disbelief. Fear. Resentment. All checks out in his glare.
"The magic of all the ponies in this world will soon be gone, but it is for the best. It's to protect you."
>"From what? Who?"
"From yourself."
>"What the fuck?"
"It sounds strange now but you will thank us later. It's better this way."
>"Listen to yourself, man. You've lost it, you're insane. How can you commit such atrocities and then try to justify them with a higher cause? That's like the worst villain motivation ever."
>Twilight on his lap is waking up so he switches his attention to her.
>"Are you okay? Twily?"
>Taking this opportunity you leave the room where the last line was held and broken.
>The hallway to it is littered with bodies of the defeated but still living guards.
>Your Lady didn't take death lightly so none of your assaults through the ages involved any significant bloodshed.
>With a magic absorbing sword in your hands what was there for you to fear?
>Undefeated, you always marched forward, breaking spears and spells alike, the cold cosmic hunger of your steel storing the stolen power.

>Princess magic was as useless as any other.
>Discord usually tried a few tricks before losing his magic as well, retreating back to his realm - after all, it was your world's Discord who discord-proofed the armor you wear.
>Rainbow Power wasn't anything special too.
>The power of Love was nothing against your own.
>And the Elements, well, you had one embedded in your helmet. Loyalty. And one right at your heart, under the armor. Kindness.
>Your Twilight ripped them from that tree, for there was no purpose in them anymore.
>Only the Element of Magic still remains there, alone on the tree that stands above the scorched wasteland left by Daybreaker.
>Other worlds' Elements, if still intact, never had any effect on you, just like they wouldn't if used on anyone with friendship in their heart.
>Against someone who isn't evil ponies are powerless.
>Through the broken stained glass you see the Empire's clean-up squads flying in to control the population and extinguish what's left of resistance.
>But also to help the wounded and comfort the panicking ponies.
>Even in conquest she's benevolent.
>In the sky you see the flying fortress, the ill omen spelling inevitable doom for any world below it.
>The Empress rarely travels in the fortress herself and today is no different.
>This world is innocent, she doesn't need to intervene.
>But now the sky is burning. The city is burning. A small sacrifice for the future of this world, but a drastic one nonetheless.
>Your name, as well as hers, will be cursed, despised through generations. But that doesn't matter. They may hate her but she still loves them.
>Behind you princess Twilight quietly walks past, not daring to look at you, wings close to her body in shame. Next to her is Anonymous, head hanging low. 
>Other princesses await the duo at the end of the hallway. All magicless. All regular ponies now but still alive.
>Twilight's Kingdom will breathe new life in this world. They will all live as they were.

>Nothing will change for them except for the fact that they can never have magic of their own again.
>Only the Empire will be allowed to provide it, controlled and safe.
>The ponykind isn't ready for a gift like that, and so those who are bestow it upon their clueless children.
>Ponies rely on it too much without understanding it, endangering themselves, so it's only fair.
>They will be ready some day. The best minds of all worlds already learn discipline and proper uses of magic which Twilight gradually returns to them in her private academy.
>Even if they are bitter and hostile at first, her students see the light and join her cause in the end. Every single one of them. They are now part of the Empire's forces.
>But none are as close to her as you are. The first and the only Knight, Anonymous.
>Now, as your thoughts drift back to her you feel her calling.
>Just closing your eyes and focusing on that is enough. You open your eyes and you now stand before her throne.
>The ponies in the evening throne room, visitors from all over the Multiverse, are leaving in haste now.
>They know better than to stand between the Empress and her Knight.
>In the dim light only Twilight's eyes glow, focusing on your figure.
>But the ominous image is dispelled by her cheerful voice.
>"Anon, you're back! How was it?"
"Eh, not too bad I guess."
>"Any vows of revenge?"
>Twilight giggles and her eyes sparkle with curiosity.
"Just the usual. Cadence and Shining were very eager this time though. Today's phrase of choice was "Disgusting creature."
>A bright chuckle is heard from the darkness of the left side of the throne.
>"That's a first, pff."
>It is a voice you're happy to hear.
"Flurry? You're here again? Glad to see you still hang out with your auntie."
>"Well, she won't let me follow you out there in the field, so what else is there to do? I'm just sitting here all day, reading...bleh...books."
"Listen to that filly, Twi, can't you let her out for some fun with uncle Anon?"

>"Absolutely not!" a smile betrays Twilight's serious glare she shoots at Flurry. "You won't be able to handle it, young lady."
>"But..."
>"We've been over this, sweetie."
>Disarmed, Flurry just pouts.
>"Ugh, fine, I get it. I just want to help, princess of overprotection."
>"Flurry Heart!"
>Standing up the "young" alicorn unfurls her wings and, laughing softly, walks near you to brush your arm with one of them.
>She is even taller now than Twilight was back in the day, when she managed to rescue her baby niece from beneath the Crystal Empire's frozen ruins.
>"You two have fun now."
>And she's gone, leaving you and Twilight a bit flustered.
"Shall we?"
>Twilight nods and leaves her throne. You follow her through the softly illuminated hallway.
>Passing near a window you see the city, still living, still thriving. Twilight's academy stands tall in the center of it.
>You remember when this place was nothing but charred stone after Daybreaker's initial outburst.
>Now the capital of the Multiverse is rebuilt and repopulated with different ponies.
>It's still the same old Canterlot. Almost.
>Though you still consider Ponyville your home, even if it was never rebuilt. You remind yourself to visit some time soon.
>Have to bring fresh flowers for all your friends who are still down there...
>Arriving to your chambers you can finally set your sword aside. In this closed dimension no one will ever find you two.
>Twilight approaches the weapon and, lighting up her horn, absorbs today's harvest.
>Alicorn magic envelops her body and her eyes light up with a green smoky glow.
>Filling herself up she smiles at you, still fuming with dark energies, mane flowing with stars.
>You come closer and give her muzzle a kiss. The crackling of alicorn magic hits your armor but it just tickles you.
>Twilight is not shy about her form anymore. She knows you love her no matter how she looks.
>The pony lifts your helmet with her hooves and you finally decide to take your armor off.

>You only now notice how tired you actually are. Your Lady knows that as well so she nods her head towards the shower.
>It feels nice to wash away all the day's events with hot water. Everything is fine.
>It's even better when you get out and see your little mare waiting for you to join her in bed.
>Her eyes are still glowing, but not for long, as your hug lifts all her worries.
>She is completely relaxed now. It's so nice to see her like that.
>You remember as if it was just yesterday, she was so afraid of herself at first, trying to push you away and then begging you to stay with her.
>Desperately trying to envelop herself in your embrace, forget the horrors of that one week when she lost everything important to her.
>This habit still lives on and Twilight always tries to get as close to you she can, wrapping you both with the blanket so you won't get separated even for a moment.
>As you give Twilight another soft kiss your memory wanders yet again back to those dark times. 
>How she screamed and cried, asking you if she's still your little pony princess over and over again.
>Asking for validation through affection. Feeling herself changing irreversibly and being terrified at the thought of you abandoning her.
>You never did. You never would. But feeling unsure she became obsessed.
>Sex became a necessity for her, to know that you still need her, that you at least have a use for her, even on that level.
>It was so bitter and degrading, but with you she could forget herself and she wanted that more than anything. 
>Amplifying her senses with magic she became addicted to the feeling of mind-breaking ecstasy, always being disgusted with herself afterwards.
>Of course those times have long since passed. Your word is enough for her to feel reassured now.
>You are a proven constant in her life, a beacon of hope for a brighter tomorrow.
>You two are still just as close as ever, even after decades of bringing the Multiverse to its knees before you.

>The feared and revered Empress, "vile", "cruel" and "despicable", is a little fuzzy bundle of warmth and softness in your arms.
>And you like it that way.
>Tomorrow is a big day. Another world is welcomed into Twilight's Kingdom.
>All the official business will surely be boring as usual, so it's better to catch some rest now.
>Twilight is already snoring in your cozy snuggle wrap.
>Powerful beyond any pony's wildest dreams she is still so vulnerable, even if she only shows it to you.
>Even when she's happy she can't seem to forget her burden.
>Traveling through time and space is so easy for her she moves entire planets through dimensions and ages.
>But even moving in time of other worlds she can't move back in her own. The only one that really counts.
>She can't prevent what has happened, as if her very presence there signifies the inevitability.
>More than one time she tried to remove herself from this world entirely so that the timeline would be broken, but you stopped her. You had to.
>Even though a mere chance of setting things right was enough for her to try, it's not a sacrifice you could accept and deep inside she knew that.
>It didn't make it easier, but it made it logical. Something to hold on to in the maddening spiral of the existence she despised. She just had to move forward.
>You hug your little Twily closer.
>Following her example you drift off to sleep, seeing a familiar dream.
>In that dream, Twilight still lives with you in Ponyville.
>Her friends, still alive and well, are gathered in your small house on the outskirts of town to congratulate your wife.
>Of course they were the first to know that you'll be having a baby - your third - sooner than you actually planned.
>Twilight is laughing and there are tears in her eyes. Tears of happiness.
>You can't possibly notice it, but in your sleep you are crying as well.