Equestrian Souls

by Eclipse Guardian

Rating: mature
Tags: Random, Adventure, Princess Celestia, Twilight Sparkle, Anthro, Main 6, Princess Luna, Gore, My Little Pony: Friendship is Magic, Alternate Universe, Other, Romance, Science Fiction
Length: 3499

When Twilight accidentally possesses Princess Luna while trying a new spell, the two begin trying to cope with their new condition as she and the princess begin to uncover a plot to seize everyone's souls.

"It was just a spell, a simple one at that. Well, until I took over Princess Luna's body by accident. Now I'm afraid that Equestria may fall to an unknown threat thanks to my blunder."

Souls are a fickle thing, easily corrupted or swayed by dark forces if ones will isn't strong enough. Princess Luna knows this better than anyone, even as her own soul shares its space with Twilight Sparkle.

With Equestria in its most peaceful era since the Unification of the Three Tribes, it remains unknown to threats from the 'Outside'. Princess Celestia leaves Twilight and Luna in charge without the knowledge of their predicament, to deal with the dragons. This leads both mares to find and eradicate an evil presence, before it unleashes an even bigger threat to Equus.
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-Mild Gore-
-Some Sexual Themes, but no Sex-
-Transdimensional Included-
-Anthro-

Published 2016-06-30 03:30:01 UTC
Last updated 2016-06-30 03:30:01 UTC

Princess Sparkle

Equestrian Souls

Twilight Sparkle was a researcher. An avid researcher. She was always looking for new spells to try out and apply to her ever growing mental library. Living in Canterlot didn't help, until she was a student at Celestia's School for Gifted Unicorns. The Royal Library was open to her later, only until Princess Celestia herself took her on as her Private Student.

Books upon books, scrolls covering almost everything from levitation to transformation, the various walls and shelves were covered from top to bottom with such literature. Twilight perused these whenever she could during the day (even at night when everypony else was asleep), she had read most of the many books and scrolls the library had to offer.

All, but the restricted section.

This wing of the castle was sealed off to all except for the ones who had royal permission, and the Princess herself. The spells contained within were kept out of the public eye, due to how dangerous they could be if they fell into the wrong hands. Wards were placed all over the walls including the gate leading directly into its depths.

Wards Twilight Sparkle had just bypassed without anypony realizing. It wasn't an easy task, the wards had several alarm spells embedded in their frame work and would alert both Princess and her guards if anypony tried to break, or teleport into the restricted section. Sure it wasn't simple to disengage the locks and disarm the alarm spells temporarily, but Twilight managed after an hours or two.

Currently, the studious and curious mare was peering into a thin red and black book, looking over a peculiar spell which was described in the utmost detail, unfortunately the last page was missing strangely. 'Astral Projection.' Twilight mused thoughtfully to herself stashing the book into her bag. 'This sounds like it could be used for a closer look at the stars...hmm I'll take it. But why was such a simple spell locked in the restricted section?' Shrugging to herself, Twilight left the wing and reengaged the locks heading back to her room within the palace.

The lavender librarian was visiting her teacher Celestia for the weekend, wanting to catch up and study with the Princess like old times. Celestia allowed Twilight to look within the restricted wing of the library during the day but only while she had guard with her. Twilight didn't the guard much, she was more interested in the ancient tomes, besides she wouldn't brings out books or scrolls she wasn't allowed to.

Well, until she came across the book of 'Astral Projection'. For some reason she just couldn't get her mind off of the dusty old tome, her curiosity just couldn't sated over night without looking into book at least once. So on her last day at the castle, she snuck into the restricted section and grabbed the book in the dead of night.

Twilight quickly opened the door to her chambers then quietly closed the behind her with a small 'click'. She sighed in relief, glad no one had caught her, especially her beloved teacher. She only once or twice in the past when she was a filly did she attempt to sneak in, but was always caught by her mentor. After a good scolding she never tried it again. 'Until tonight.' She thought with a some shame. “Anyway, I'll return it before the night is over so no worries.”

Nodding to herself, she reached out a hand and pulled out the chair from her study desk. Twilight slipped off her side bag and retrieved the borrowed book then setting open on the desk. “If I got this right, all I need to do is reach deep within myself and find my core.” As a precaution, Twilight set up several wards of her own. “Don't want anypony to hear this spell if it goes awry and causes an explosion or something.”

Twilight's horn lit up in a magenta glow, she went over the formulas in her mind before closing her eyes in concentration. Sweat covered her brow as spell began, Twilight felt a tingling sensation all across her body like static electricity.

She looked deep within searching for her magic's core, when she found it she gently wrapped her herself around it. She felt a tug, she shrugged it off. Her body began to spasm without her knowledge. Her horn glowed an ominous blue, purple wisps of energy flowed out from Twilight's body as it shook. Deep within, Twilight suddenly felt herself pulled roughly backward and crashed into the ceiling, but without any pain. 'So it was a dud, but why didn't I feel anything from hitting the roof?' Looking up curiously, Twilight's eyes bugged out at the sight of herself still at the desk. “What?! What am I doing over there?!” Panicking, Twilight ran toward her body and attempted to grab her arm, only for a blue barrier to send her toward the floor. “What just...” Twilight looked down and noticed that she was transparent, and had a ghostly magenta wisp-like appearance.

“Am...a-am I a spirit!?” She loudly exclaimed as she stood up and ran back to her prone body. “This is very bad! What if the Princess finds out!? She'll be here in the morning!” She began pacing around the room, before an idea came to her. “Wait! Maybe Princess Luna will know something!” With that thought in her mind, Twilight phased through the door with a shiver. “That will take a while to get used to.” Shaking her head Twilight hurried through the corridors heading for Luna's chamber knowing the lunar princess was getting ready for Night Court.

Ten or so minutes later, Twilight stopped at Luna's bedchambers, while two Night Guards stood stoically guarding the door. Twilight in her panic forgot about the dark armored thestrals and stood before them waiting to be questioned. A moment passed and with no actual words coming from the guards, Twilight sighed in relief. 'I hope Luna isn't done yet, I need to fix this fast!' Oddly enough, Twilight easily phased through the doors leading to Luna's room despite the many protection charms on the doors. “Maybe they didn't take spirits into account?” She pondered as she stood in the middle of the room.

She didn't see Luna anywhere, but the sound of the running water alerted Twilight to the closed bathroom. “She must be in the shower.” With time on her hands, Twilight took that moment to study her astral form more closely. “I'm the same shade as my magic, no clothes (obviously), I can't seem to access my magic.” She thought with a pout, before looking in the mirror. Her tail was blowing in an unseen wind, along with her mane. Her body was completely transparent, and she couldn't see her eyes or mouth anywhere on what's supposed to be her face. “This is creepy. I have all four of my limbs, but my horn is useless and my eyes are missing.”

She was cut from her observation at the sound of water being turned off. “I hope Princess Luna can see me, I don't like being without my magic for long.” She heard foot steps as watched the door open and Luna stepped out...naked. 'Ah! Look away Sparkle, look away!' Twilight tried to turned around but she was enraptured by the Lunar Princess's beauty. Large breasts, hourglass frame but smaller than her sister's, long shapely legs, a long flowing star-speckled mane and tail, lovely silver eyes, a beautiful dark blue coat and a round bouncy rear. 'I really shouldn't be doing this.' Despite her thoughts, Twilight was always somewhat smitten with Luna even after her return from the Moon.

Luna stepped past Twilight toward her dresser, pulling open one of the drawers. Twilight followed every movement she made, as the lunar mare took out a red lace pantie. The ghostly Twilight paled, taking a step back away from Luna. 'I should come back later.' Again her gaze was drawn to Luna as she slipped the underwear over her legs and around her hips.

Twilight grimaced with slight envy, her own body wasn't much look at by her standards. She was only a C-cup, her hips were average as the same with her flanks, she wasn't the tallest of her friends only standing over Rainbow and Pinkie by a few inches. Twilight was jealous of Pinkie's and Fluttershy's bust lines somedays and especially Rarity's gorgeous looks and Applejack's and Rainbow's toned bodies. 'I don't really care about my appearance but being around such ponies like my friends, makes me a bit self-conscious.' Luna was beyond beautiful, but her sister Celestia was the epitome of sexiness and femininity. Both of them made Twilight feel like a petulant child with her slightly pudgy body.

With a growl, Twilight made her way over to Luna to catch her attention by waving a transparent hand over her face. The Princess didn't even flinch. “Even an Alicorn can't see me? What did that spell do exactly, ignoring the fact that it pulled me out of my body?” Twilight was getting frustrated, with her ever growing envy, her fear of being scolded by Celestia for sneaking into the library's restricted section, and the thought of being stuck as a spirit for the rest of time. “No!” She yelled, reaching for Luna's shoulder.

But instead of grabbing it her hand slipped into Luna's body. “Gah! Not good!” She felt Luna shiver.

“Wh-what was that?” Luna asked dropping the brush she was using.

Twilight felt more of her being pulled inside of Luna. “I can't pull out of her!”

Luna felt a pleasurable tingle run up her spine. “Mmm...”

The astral Twilight continued to fight,but found her both her arms stuck in Luna's back. “Why can't I pull out!?” By this point both arms were completely inside of Luna, much to Twilight's rising panic. “Princess Celestia will kill me if she finds out about this!” Next she found her legs being pulled inside of Luna's, while the lunar princess began to pant.

“What's this strange feeling? I-I hope Tia didn't mess with my body wash again...ngh.” Luna moaned as the tingle spread throughout her body.

Twilight's eyes widened further as her torso was entirely inside of Luna with only her head and neck free. “Discord's Hell! Celestia is gonna kill me!” She screamed as she completely phased into Princess Luna.

Luna felt a jolt as she began to lose consciousness. “Oh my, Faust...” She groaned before blacking out.

Twilight awoke the next morning with a mild headache. “Ah, what a strange dream. I really should stop staying up for several nights...on...end...” She trailed off at the sound of her voice. “Uh, did I catch a cold or something? Because I sound an awful like Princess....Luna...” She froze as she lifted her hands up to find they were dark blue instead of her usual lavender. Following that, she looked down to find a pair massive mounds on her chest. “I'm...I'm...” She sat up noticing she somehow was laying in Princess Luna's bed, and in her chambers also.

...

“I'm Princess Luna?!” She screamed in Luna's voice.

Twilight was horrified by the prospect of stealing another pony's body, especially since it was one of her friends, it was even worse since Luna was royalty and the sister of Twilight's beloved teacher! “Wait maybe this is a dream! There's no way I could ever steal Luna's body in real life!” Nodding to herself, Twilight took her left hand and pinched her right hard. “Ow!” She felt the pain alright but she was still inside of Luna. “Okay, try again, Sparkle.” This time she looked at Luna's large breasts and pinched the left one. Twilight expected pain, but instead she let out a little moan as her fingers squeezed the soft flesh. “Oohhkay!! Enough of that!”

She bounded out of the bed and stood on wobbly legs, unused to her new-found height. Twilight again looked down at Luna's chest with a stray thought. 'Wow, Luna's breasts are much bigger than mine.' Curiosity overpowered her panic for a moment as she squeezed her new assets together. She stifled another moan as her fear rekindled. “I have to get out of her somehow.” She made her way to the door aiming to head back to her own room and hopefully reverse the spell. She was only step away from the door knob before realizing she was still naked, and she only was wearing Luna's red panties from the night before. “I can't go out like this, I'd ruin Luna's image.” She briskly turned around and eyed the dresser Luna was using. “I sure hope there's something in there.”

Ten minutes later, Twilight walked out into the hallway wearing Luna's regalia, Luna's usual attire of: a dark blue and black dress that reached her ankles hugging her new curves nicely, a pair of high-heeled crystal shoes, and a pair of enchanted glasses to hide the color of her eyes (she found out that she turned Luna's eyes to her shade of purple and that might give her away).

Luna's guards fell in step behind her as she headed toward her chamber and away from Luna's. 'I have to fix this before Celestia finds out!' While she wasn't actually afraid that her mentor would actually harm her, she hated it when Celestia was disappointed in her.

Twilight thought on the way, going over her options. 'I could run, no no that's a really bad idea since I'm still in Luna's body. I wonder if Princess Luna is still awake in here, I have to apologize for accidentally possessing her. Oh I hope she doesn't banish ME to the moon for this. Even if I am extremely sexy now...ah stop thinking about that!'

“Princess Luna, Your Majesty are you sure you should be up and about right now?” One the guards asked.

Twilight regarded him for second then continuing on. “Why do you ask?” She gave the guard a smile with her best Luna impression.

“Well, we heard a noise in your chambers, Princess and found you passed out on the floor.” The other said.

'Oh, so it must have been them that put me into Luna's bed.' Twilight mused with embarrassment. 'Then they must have seen Luna's naked...oh damn.'

“But don't worry Princess, we made sure keep our eyes closed.”

Somehow that just made Twilight even more embarrassed. 'Great, I just hope they didn't cup a feel by accident.'

Sometime later they made it to Twilight's room and she stopped them from following her. “I-er We are gonna check on...um, Twilight Sparkle just to see if she wants to chat with Us.” She stammered trying to copy Luna's use of the royal We.

Both stallions gave her confused looks before taking up posts outside the room as she closed the door. “Phew, finally. Now I can see if I can reverse this.” Turning around Twilight looked at the desk she was sitting at last night. Only it was empty, her body was gone. 'WHERE IS IT?!' She screamed internally.

'Twilight Sparkle, would you please not disturb us so early in the day.' Twilight's borrowed eyes widened in shock.

“Princess Luna, oh thank Celestia you're okay!” Twilight said with glee.

'Of course, We're okay. Why wouldn't we...be?' Luna quickly realized she couldn't move her body and that she was not in her own room. 'Twilight why are we in your chambers? And why can't We move our body?'

“...Um, I may have botched a spell last night.” Twilight weakly grinned.

'And why do you sound like Us?' Luna's tone sounded irritated.

Twilight hesitated, than blurted out. “I am so so sorry Princess Luna! I used a spell that forced me out of my body, so I went to find you, to see if you knew how to reverse it! So I tried gaining your attention but you couldn't see or hear me, so I tried grabbing your shoulder but I...I...” She trailed off not wanting to finish.

Luna sighed. 'And you accidentally possessed me.'

“Yeah, I am so sorry Luna.” She began to tear up as her shame rose.

The lunar princess mentally shook her head. 'It's alright Twilight, just cast the spell again, it was called 'Astral Projection' wasn't it?'

Twilight looked at her mirror. “How did you...”

Luna snorted with amusement. 'It was a spell Starswirl the Bearded created, out of pure curiosity. He used it to swap places with his apprentice Clover the Clever for a day when she complained about not being important to his research. Mind you, she was still very young at the time.'

“They did? Hmm, I didn't read about that.” Twilight's panic was replaced with a confused expression.

'Just recast the spell and return to your own body than we'll-Twilight, where is your body by the way?' Luna asked as Twilight looked around.

Twilight's panic returned. “I don't know! It was here last night!” She ran around the room, the bathroom, her bed, the balcony looking for her body. “It's not here, somepony must have taken it!”

'Twilight calm down. It has to be in the castle somewhere still. Maybe my sister went to check on you earlier and found it. Your body is most likely in the infirmary.' Luna calmly suggested.

Twilight stopped pacing and brought a hand to Luna's sizable chest, taking a deep breath. 'In and out, in and out.' With her breathing finally under control, Twilight made her way out the room. “I hope Princess Celestia merely took 'me' to the medical wing.”

'By the way Twilight. We saw you fondling Our breasts earlier.'

Twilight stepped back into hallway gestured for the guards to follow. 'You did!?'

'Heh, We did. But we -ahem- I thought I was still dreaming at the time. So why were you may I ask?'

Twilight bit her lip. 'Again I am so sorry about all this. It's just that, they're so much bigger than mine, I couldn't help myself.'

'Oh are you jealous of Our figure?' Luna asked in a mischievous tone.

'No! Um, maybe? ...Okay I am. I'm not exactly the most pretty of mares.' Twilight grumbled.

'Nonsense! You are plenty desirable Twilight Sparkle!' Luna pressed.

'I wish. It doesn't help much when most of your best friends have better assets than you.'

'You're still young Twilight. You're not finished growing yet.'

'I'm only 19 but...Yeah, you're right. Sorry Luna.'

'It's alright my friend.'

Princess Celestia stood before 'Luna' with an amused but worried smile. Her fine white silk dress hugging her figure.“So that's what's happened Luna. But don't you worry about Twilight, I already sent her home. She was perfectly fine when she left.”

Twilight and Luna both stood there silent as Celestia told them of how Twilight's body left an hour ago before they arrived. 'L-Luna, we should tell her...'

'I know, but it wouldn't be wise since we can't find that spell and we shouldn't worry my sister while she isn't here in Canterlot.'

“...Erm sister, when are you going to return home exactly?” Twilight asked as she felt another panic attack coming on.

“In a weeks time, Luna. The dragons are causing issues in the East, so I'm needed to treat with them.” Celestia stepped into her chariot. “I'm leaving everything to you, sister. Good luck.” With that her pegasus guards took off into the sky dragging her chariot behind them.

Twilight grit her teeth. 'We are so bucked, Luna.'

'I agree this situation is very problematic. Since for some reason your body got up, chatted with my sister, then left the castle for Ponyville an hour ago, and I'm still here in my body.' Luna said with a mental grimace.

'But, how is my body moving about by itself without me? That doesn't make any sense!' Twilight replied as she watched Ponyville from a distance.

'I know, the spell was developed for two souls to swap bodies. But for some reason I'm still here.' Luna said with confusion and not a small amount of worry.

'I don't like this Luna. What if somepony else has possessed my body?! I am the Element of Magic. Any one of my enemies could have stolen it for their sick ends!'

Luna sighed. 'That might just be true.'

Twilight narrowed her eyes. “I'm gonna send a letter to Spike.”

'Sounds good, but make sure you sign my name on it, just so the one who is in your body doesn't know they've been uncovered.'

'They might already be aware that I'm inside your body, Luna.'

'Indeed.'

...

Unbeknownst to the both of them, a small metallic creature watched them from the corner of the gardens. “Phase one proceeding as planned. Equines unaware of our presence. Continuing to monitor.”

Author's Note

This is my first crossover story, and the first with actual sexual themes in a story of mine. So I hope I did okay for the first chapter.