Feedback for this story was lacking, so I've decided to put it on hold despite my personal enjoyment for it.
 
>What’s happening?
>Everything is… black.
>From somewhere voices speak over one another.
>There’s a ringing and a cold force against your body.
>Are you on the ground?
>Why is your head spinning.
>The world doesn’t relent it’s assault on your senses.
>Can’t… make out anything.
>It’s bright to your vision, burning almost.
>These voices, they sound shocked.
>Concerned maybe?
>So far away…
>You try to move, only for your head to reel back.
>Something isn’t…
>”H-y, -h-t i- t-at --in-?”
>They’re still talking.
>Inderscenabley so.
>Again, try again.
>Force yourself up.
>Do it…
>Through the pain, you send a limb to the ground, straightening it.
>Now stand.
>Your body stretches in a foreign way, and your vision has quadrupled.
>Something’s not right…
>Your…
>”Wh--e -id -t c--e -r-m?”
>What is that?
>Things are becoming less abstract.
>But your appendage…
>This isn’t...
>”H-y! A-e -ou -k-y?”
>Your body is seizing up again.
>What’s going on with you?
>The ground… it’s pavement.
>You’re outside.
>Voices, they’re shouting now.
>”So-e--dy c-ll -he --ard!”
>At you?
>Look at them.
>Why is it so hard to move?
>Come on.
>Your blurry vision begins to shift over.
>There’s voices coming from all over.
>What are those things looking at you?
>So many…
>They’re…
>”It’s m-vi-g!”
>Ponies.
 
>Why are they staring at you?
>Your body falters once more and your face hits the pavement.
>This… your body.
>What’s wrong with it?
>”Where are the guards?!”
>Guards…
>Why are they getting guards.
>Your head can’t make sense of the situation.
>It pounds against the inside of your skull, quaking within you.
>Such pain.
>Again, your limbs fail you as you’re only able to roll onto your back.
>The sky…
>It’s blue color stretches across your vision.
>How long do you spend staring at it?
>They still holler at you.
>You can see them now, up in the sky there are clouds.
>Spinning around and around and around…
>Eventually, their paths grow shorter as they encircle one singular spot.
>And your vision is back.
>”Stand, creature!”
>The voices have returned, and now you understand them.
>”By decree of the Princess, we order you to stand!”
>Princess?
>Why do they shout at you?
>They want you to stand.
>Your legs... how do they work?
>Head still pounding.
>”Stand!”
>Do it!
>Your legs give out and you fall forwards onto your knees, catching yourself with your… hands.
>You look up and see the armored ponies before you.
>They’ve backed away a bit, and look more afraid than anything, like they’ve never seen you before.
>Why’s everything wrong?
>Again, you try to support yourself on two legs.
>There’s a rapturous murmuring amongst the crowd around you.
>The guards eye you carefully.
>You’re in the city, the white one.
>What’s its name?
>Why is everything so hard to remember all of a sudden?
>Something isn’t right with what’s happening…
>Somehow, you made it onto your feet.
 
>”Follow us. We are not afraid to take action if necessary.”
>Why are they acting like you’re a threat?
>A spear is pointed at your back.
>They want you to follow.
>Your steps are heavy, and you stumble.
>These guards, they’re leading you somewhere.
>The castle, it’s a castle.
>Everything is flying by you in a daze.
>Stares, words, aches and pains.
>Your feet are unsteady, like an infant learning to walk.
>Something’s off…
>You're in the castle now.
>It’s grand halls stretch before.
>Everything’s happening so fast.
>This place is…
>Those double doors.
>What can’t you remember?!
>The doors open…
>Your eyes dilate at the impossible sight before you as time crawls to a halt and the banging in your head pounds against your skull one beat at a time.
>”Princess, we found him.”
>”Thank you, Stonewall. Would our guest like to introduce himself?”
>You, they’re talking about you.
>Himself?
>The Princess is approaching you now.
>”Please, tell us,” her voice is slow and intoxicating. “What is your name?”
>Before you is a snow white alicorn, adorned in a golden crown and jewelry.
>Your mouth opens in abject horror at this sight.
>This is not possible.
>Why is this happening?!
>Slowly, you form one, single, solitary name.
>A name you have not uttered for thousands of years.
“Anonymous...”
>”Hello Anonymous,” she smiles, baring her teeth, her gaze narrowing in on you “I am Princess Celestia.”
>This…
>Now you know what is wrong.
>You are Princess Celestia, and you are not in your own body.
 
>No, this can not be happening...
>You’re staring straight into your own eyes, through another’s.
>It’s a horrifying experience.
>These legs and arms… you look at them in exasperation, the pounding in your head not helping the situation.
>Your foreign hands reach for your face, making contact with alien flesh and hair.
>This is sickening.
>You dare to look back into your eyes, but no, they aren’t yours anymore.
>There’s something else behind them now.
“How… How did you-”
>The words are hard to choke out.
>Slouching over, you gasp for breath.
>Your mind is racing, the strange heart inside of you is beating out of control.
>”Anonymous, are you okay?”
>His voice, your voice, feigns false sympathy, but is subtle enough to go unnoticed by the guards.
>Once again, your eyes move up to your imposter, narrowed in pain and anger.
>Your puppet-body devilishly smiles back for a split second before returning to the previous false concern.
>”Guards, please, fetch a medical team immediately! All of you!”
>The two of you never break eye contact as the uncertain shuffling of hooves is heard behind you.
>And then the doors close.
>”Hello, Celestia. Having fun today?”
“Anonymous-”
>”Uh-uh,” he silences you before you can continue. “We don’t have much time alone Celestia. Make it count.”
>With the sense of urgency, your voice returns with newfound strength.
“Is Luna okay?”
>Your voice quivers with the question.
>Anonymous is caught off guard, pausing, before smiling.
>”Oh Celestia, always the selfless one.”
 
>He begins to slowly pace around you, confidence rushing through his stolen body with each stride.
>”Your sister is fine, I assure you. But please, show some concern for yourself. After all, I’m in control now, aren’t I?”
“Why are you doing this?”
>Continuing to encircle you, he responds in his demeaning voice.
>”Insurance, Celestia. What’s the fun in making demands if no one will listen to them?”
>You’re sickened at the prospect of obeying any demands from this monster.
>He begins to walk away from you and towards your throne.
>”Just think of all the things I could do to your ponies. I wonder…”
>Reaching the throne he sits down, facing you once more.
>”How easy is it to do something like… declare war on the griffins?”
>The absolutely terrified look on your face makes him laugh.
>”Oh, it’s good to be the Queen! But wait… that’s right,” he says, his mistake made on purpose.
>He descends from the throne, approaching your still form until he is a mere few inches away.
>”You’re not the Queen, are you, Princess?”
>Laughing once again, he walks over to a window, his back facing you.
>”But I’m sure you’re curious how I did it, right? I mean- who wouldn’t be?”
>As all of this happens, your stomach leaps.
>You don’t want to be here; this must be a nightmare.
>Any moment now you’ll wake up and everything will be okay.
 
>”Do you remember how long?”
>He expects a response from you.
>Mustering all your strength, the most you can do is a weak whisper.
“Yes…”
>In a moment, he’s upon you, shouting.
>”Because I do!”
>All too quickly he regains his composure, backing up from you.
>Your heart is racing and your head is pounding.
>”Three thousand two hundred and eighty-six days,” he states coldly.
>”Sorry I couldn’t wait for an anniversary. I’m not like your sister.”
>The stranger’s hands at your sides become fists, tense with rage.
“Don’t you dare ever make that comparison!”
>The teeth in your mouth are grinding against themselves.
“She is nothing like you.”
>You spit each word through gritted teeth.
>Anonymous looks at you curiously through your eyes.
>”Oh- did I strike a nerve? Sorry Celestia.”
>His sympathy is dry and fake.
>”Even you must be able to see it though. Where did you gain your sense of humor for punishments from?”
>”Discord, the being of chaos made up of so many different animals, turned to uniform stone.”
>”Your sister, whom only wanted ponies to love her moon, banished to her crown jewel.”
>”And then there was me… not that I can blame -you- for that one.”
>”But as I was saying, when one spends so much time in the ethereal realm, they pick up a few tricks.”
>The ethereal realm… it should have been impossible to escape from there.
>Should have been.
>”Do you know what it’s like there? Simply dreadful, I wouldn’t recommend it for a vacation. You can’t tell up from down; everything’s such a blur of color there. Almost impossible to distinguish one thing from another…”
 
>The sickening smile returns to his face.
>”But I found you. And I spent oh so long learning how to kick out your spirit.”
>So that’s what he did then: he used his banishment to grow in strength.
“Then why didn’t you just leave me there?”
>His careful pacing around you resumes.
>Where are the guards?
>This feeling of being helpless… you want to escape it.
>You want to curl up in a ball and let all of this be over.
>For the first time in years, you’re scared.
>”Because Celestia, I don’t have a vendetta against you personally. And remember, I do need you.”
“I’d rather die.”
>Your words came out naturally.
>The last thing you would dare do would be to help this monster.
>And then the seizing in your body returns in full force.
>You fall to your knees and grasp your head, tears beginning to form from the pain.
“What did you do to me?!”
>Your shout of horror only serves to make Anonymous chuckle once more.
>”Oh please, Celestia, I didn’t do anything to you. In fact, you weren’t supposed to wake up as soon as you did, but color me impressed. You’re a strong one.”
>He stops in front of you, looking down at your pathetic form.
>”Besides, I’m far too attached to my body to harm it in away. While yours isn’t quite as cozy, I promise not to damage it too much.”
>Turning away from you, he looks back and says all he has to.
 
>”Your ponies however… they’re a bit more expendable.”
“Please-”
>The first tear rolls down your fleshy cheek.
>Your breathing grows haggard.
>In not but a mere whisper, you submit.
“What do you want?”
>”That’s the spirit!” Anonymous cackles, turning back around to look at you properly.
>”Oh poor, broken, lost, Princess Celestia...”
>He begins to approach your sullen body.
>You can’t take this anymore.
>The world begins to lose it’s color.
>”As I said before, you’re not the Queen, are you Princess?”
>Slowly, he crouches down to face your slouched head.
>Your head is on the verge of collapsing.
>Delicately lifting your head with a hoof, he looks you in the eyes.
>”Where is your mother, Celestia?”
>At last, you know what he wants.
>Revenge.
>And then the double doors opened, and you slipped away.
>”Anonymous! A-e yo- o-ay?”
>”Pr-nce-s, w- -ad t- -- all -he -ay t- --e b-r-a-ks...
>”Ano-y--s!”
>”Is -- -ll --ght?”
>”G-ar--, -ui-ly! T-k- --m t- --e i--irm--y!”
>All too quickly, the world falls out beneath you, fading to black.
>Your headache goes with it.