“So are you a super secret monster pony too?”

Twilight sat as still as she could on the bed. How had it spiraled out of control like this? Go to Ponyville, oversee preparations, hole up in the library and search for a way to stop the Dark Mare, avoid interaction with anypony not important. Come sunrise, she would think of something and then Celestia would see her folly and defeat the Mare in the Moon -- for good this time. It was a simple plan she'd had, and her best plans were simple. It was foolproof.

The problem with foolproof plans was that one spent so much brainpower making sure the common pony couldn't ruin it that it was easy to forget that your associate was a veritable genius who actively worked to undermine your efforts. Even then, there was no accounting for the madness that was this pink... thing, in the room with them.

“No.” Sunset didn't look at the pony literally breathing down her neck, instead continuing to slave over the spell she would need to cast on Twilight.

“Well that's okay! I mean, cupcakes wouldn't be all that special if there weren't muffins! And I know for a fact that muffins can get really tasty! See, because cupcakes might have that tasty frosting on top with sprinkles to make 'em look extra pretty but they usually don't have stuff like blueberry in them like muffins-- ooh, but I did bake a batch of blueberry cupcakes once and those were extra tasty! So maybe you both got blueberries in you and that would super duper awesome!”

Her name was Pinkie Pie. She was talkative, excitable, so pink that it had to be illegal, a scientific impossibility that caused other scientific impossibilities, and she was now privy to Twilight's secret.

It had been her that had organized the surprise party presently ongoing in the library. About the time her obnoxiously colored head popped into view with a belated “Surpriiiise!,” of her own, Twilight had given up. She was defeated. Equestria was going to be plunged into nighttime eternal because she hadn't had the time to look up what she needed to and make the princess see the truth. It was over, and they were doomed, so there was nothing for it but to drown her sorrows in... whatever was being served here. Hopefully something very strong. Then she would notice it, at least.

Pinkie had accompanied her the entire way to the table where all the food and drink was, rambling on about something about knowing everypony in Ponyville and how she was excited or whatever. In hindsight it would have paid to not have tuned out the finer details of the world just yet. Twilight had thought the liquid she poured into the glass was oddly colored, but she didn't care anymore. Something about making friends from Pinkie Pie, (why is everypony so obsessed with interpersonal relationships today?, she wondered) and then it hit her.

The burning in her mouth. This was no juice, and certainly not alcohol.

“Hot sauce... huh. Didn't know you liked it intense, Twilight.” Spike said.

Her mouth and throat were on fire. Her eyes were watering and most distressingly, she could feel her disguise faltering on its already shaky legs. A fragment fell from her face, and she immediately darted at speeds she hadn't thought she was capable of for the second floor and slammed the door shut behind her. She was certain she had left a trail of of pieces behind her like breadcrumbs... but it really didn't matter anymore, now did it?

She sat there, leaning against the door as the vengeful spiciness faded and her shell fell away in piece by piece, catching her breath. A part of her felt like crying, another wanted to scream. But really she felt more numb than anything. Maybe it was the hot sauce.

Why did she even care so much, she asked herself? She wasn't a pony. She didn't need the sun to live. She liked the night sky better anyway! Would eternal night really be so bad? Certainly not for her.

After a time, Twilight had stood and walked to the vanity that was set up by the small staircase, the last of her pony form shedding from her back. She looked at the creature staring back at her in the mirror, her glowing, violet eyes surrounded by darkness.

Well, she supposed referring to her disguise as a pony form was somewhat of a misnomer, since she looked an awful lot like one anyway. Four legs, two eyes, floppy ears, a tail – even a cutie mark on both flanks. The pink and white stars still stirred happiness in her heart, even if only faintly at the moment. Her special talent was magic, and nothing would compare to the joy she felt that day in Celestia's chambers when her rump was spangled with them. Of course, that moment was more than somewhat diminished when she discovered it was dark magic she was proficient with, but the fact that she had a cutie mark at all had fueled her hopes that maybe, just maybe, she could be normal regardless. For a time, anyway. Eventually Twilight had come to the decision that it would be better for everypony if she just kept to herself. Which she would have done anyway; other ponies always had made her anxious for some reason.

What am I, even? What manner of beast is so like these equine people, and yet so much more terrifying? Who would be so cruel as to allow for something like me to exist?

Why would they leave me to live with them?

A knock at the door had shaken Twilight from the thoughts that had played through her head countless times before, still with no answers.

“Twi, it's us.” Sunset's voice muffled its way through the wood, and the handle was quickly enveloped in a black cloud. It swung ajar enough for the unicorn to enter with Spike in tow, and quickly shut and locked itself.

“Sunset--”

“Don't worry about it, girl. That's my job right now.” Out of her saddlebags came a rolled scroll bearing the seal of confidentiality, which – being the mistress of Equestria's confidential information – Sunset broke without a thought. “Celestia gave me the spell for fixing your disguise, just in case something like this happened. I got you covered.”

Twilight felt some of her glumness dissipate on the wind of Sunset's assurance. Her anger toward the unicorn for getting in the way of her plans remained, but she was certain the mare had never intended to facilitate Twilight's illusion being literally shattered, and this was apology enough to her that she would accept it. The smallest of smiles graced her muzzle. "Thanks, Sunset."

The oddly warm moment ended abruptly when the sound of a door bursting open filled the suite. The source was betrayed by their ears as none other than Pinkie Pie herself. She had popped in somehow from the washroom despite having been downstairs, and laid her odd spiraling pupils on the true form of the false unicorn. The first thing out of her mouth in response wasn't a scream, or 'you're a monster!,'; nothing so simple to wrap one's head around. “Neat!,” she had said.

“Earth mare!” Sunset took the pink abomination in a tight stranglehold with her magic and yanked her close. “Explain yourself!”

“Well she ran up here awfully fast and my first thought was 'well she probably just has to use the little fillies room' but then you and this super-cool awesome dragon here went up the stairs all stiff and worried and it hit me! She must not be feeling okay! And then I got super worried because she might have been sick or something and that's no bueno, so I scrunched up into the air vent and slithered like a snake all the way up here but I ended up in the bathroom so I came through the door after I checked that nopony was hiding there and then I saw her like this and I was all like 'neat!,' and then you grabbed me and told me to explain myself so I did!”

Sunset was sure she had crushed the pony's windpipe so that she would need Sunset's permission to speak, so the unicorn was currently sitting with her mouth agape.

“Hold on a second,” Twilight brought a hoof to her muzzle in thought as she scrutinized Pinkie with narrowed eyes. “I've seen you before...”

The exuberant mare blew a raspberry. “Well, duh, silly! I surprised you three downstairs like five minutes ago!”

“No, before that!” Twilight proceeded to rack her brain for the point of reference she had for the pink mare, as the pony in question was relinquished to the floor again. Somehow her neck was perfectly functional despite the vice-grip of Sunset's telekinesis contorting it into a bent shape.

It hit the false pony. “You're the pony who I tried to talk to first thing! You ran off without a word!”

Pinkie giggled and snorted at the violet mare's behavior. “Gosh, girl; you must have your head in the clouds more than Rainbow Dash! Ooh wait! Do they taste like cotton candy?”

Twilight's expression would go on to become the dictionary definition of dumbfounded. She stared in disbelief. This mare was somehow real, actually sitting in front of her with her pink coat and pinker mane and her neck snapped in four different places, asking about the taste of clouds like they were sitting out and having lunch.

Forget figuring out what I am! “What are you???”

“I already told you! But since you're so adorably fuzzily scary looking in the best way, I guess I can spell it out for you nice and slowly.” The mare took a deep breath that somehow straightened her neck back out, but her impossible antics didn't stop there. Her hoof! Little protrusions emerged from it as the frog distended, and in entirely the wrong direction, until the pink pony's right foreleg was topped off with what could only be a minotaur hand. She snapped her newfound fingers and a chalkboard popped into existence behind her, sticks of chalk moving on their own to illustrate her tale:

“A-hem! I'm Pinkie Pie, and I have no idea what I am except a pony who likes to put a smile on everypony's face! I go with earth pony though, because I can buck a mean applebuck. Just ask Applejack!” She pointed to the charmingly crude drawing of herself on the board with her grotesque and alien and wrong index finger. “I was asleep for a really long time, I don't know how long, but I woke up one day suddenly, and I didn't know who I was! But what I DID know was that there was a beautiful rainbow in the sky, and I'd never seen something so amazing and fantastic!” Outlines of a rainbow were drawn above the crude Pinkie, bridging a gap between two triangles that Twilight had to guess were mountains. She was holding onto these small and mundane details, for fear she would go mad in the mutant pony's presence otherwise.

The chalkboard was wiped clean by an animate eraser and its green expanse was replaced with Pinkie giving cake and presents to various other ponies surrounding her. “Ever since then, I just had to share that feeling with everyone! It'd be awfully selfish of me to keep that happiness to myself, and once I got a taste of what ponies look like when they're happy, I knew what I was going to do! And so did my cutie mark!” The board was cleared again, and the chalk drew a trio of balloons with their strings spiraling together. Indeed, this was what was emblazoned on either side of the pink pony's rear. An embarrassingly eye-catching group of islands in blue and yellow on a pink sea. It certainly didn't help matters that it was being shaken in Twilight's face.

A snort of stifled giggles came from the false unicorn's right, and she found the sanity to glare at Sunset again.

“I'd swear the sun was right here in this room with how bright your face is, Twilight.” The unicorn's muzzle scrunched up, doing its absolute best to contain the cascade of laughter that threatened to drown them all.

“Pinkie!” Twilight shoved the flank away from her personal space. “Tha-- that's extremely lewd! Why would you do that!?”

“I just wanted to make sure you saw my cutie mark, Twilight.” And her face bore the most innocent of smiles as the chalkboard and its accompaniment vanished at another snap of pink fingers.

The purple mare's eye twitched. Her voice next came with unnerving calmness, “I think I need to lie down for a minute.”

Sunset, who had managed to defeat her incoming laughing fit, nodded at this. “That's actually a good idea. I need you to be still while I cast this.” She turned her attention to the intruding logical fallacy machine that called itself a pony. “As for you...”

“Hi there!”

“You'll not breathe a word about what you saw of Twilight to anyone, or you'll regret it.” Her horn lit up in flames to punctuate her threat.

“Oooh, cool beans!” Pinkie Pie marveled at the fire for a moment before donning an uncharacteristically serious face. “I Pinkie Promise to not tell anypony that Twilight is a super secret monster pony! Cross my heart,” her alien hand crossed over her chest, “hope to fly,” she flapped her forelegs, “stick a cupcake in my eye!” Her hand slapped loudly against her eye. The pony cracked a smile again. “You can't break those!”

Put off by the display, Sunset managed a “yeah, sure, whatever” before turning to rejoin her charge, who had scaled the steps up the landing where a bed lay at the top. No sooner had she reached it that the pink mare was in her bubble. “So, are you a super secret monster pony, too?”

“No.” Sunset pointedly continued to examine the spell scroll she had with her.

“Well that's okay! I mean, cupcakes wouldn't be all that special if there weren't muffins! And I know for a fact that muffins can be really tasty! See, because cupcakes might have that tasty frosting on top with sprinkles to make 'em look extra pretty but they usually don't have stuff like blueberry in them like muffins-- ooh, but I did bake a batch of blueberry cupcakes once and those were extra tasty! So maybe you both got blueberries in you and that would super duper awesome!”

“Fascinating, now please leave. I need total concentration for this.”

“Okie-doki-loki!” With that, Pinkie Pie backflipped off and to the floor, landing with a bounce.

Spike, who had watched the entire thing with equal parts wonder and horror, finally found his voice. “...So, can I go down and join the party?”

Twilight opened her mouth to deny the baby dragon his request but Pinkie zipped into the whole of his vision. “Of course! You just gotta come down and play games with me! Nopony around here has any claws so I have to do all the normal stuff most of the time.”

“Knock yourself out, Spike.” Sunset waved her hoof to shoo them away. “Nothing interesting's gonna happen up here for a while.”

“Sweet!”

“Sweet!”

The door was heard opening as the two shuffled out of the room. Sunset quickly re-closed and locked the door behind them.

“Remember how I said our first encounter with her was interesting?” Twilight asked.

“Yeah?”

“That was like food compared to what just happened.”

“Yep.”

With the manifestation of insanity gone from the suite, the violet pony-creature found she was rid of her previous penitence to fate. Somehow, Pinkie Pie had taken all the doom and gloom in her mind and thrown it away.

Unfortunately that only brought back to mind how she was utterly unprepared for the Dark Mare's return, and the fact that the sun had now completely set and the moon taken its place in the sky made those fears more urgent.

“Ponyfeathers.”

Twilight swiveled her head in Sunset's direction. “What's wrong?”

“The spell calls for dark magic. Not much of it, but...” The unicorn shook her head. “How can the princess handle that stuff...?”

Twilight's pointed ears reflexively lowered.

Sunset looked to her. “Think you could spare a teeny bit of yours?”

“Oh! Um, of course.” A blush colored Twilight's muzzle for the second time that evening.

“'Kay, just give me a second to prepare...” The unicorn closed her eyes and took a few deep, slow breaths. She leaned her head toward Twilight's. “Ready.”

The purple pony hesitated for but an instant before bringing her curved horn to Sunset's spiraling one, and they touched. Both mares briefly shivered at the sensation. Twilight willed her magic forth from the ley lines of her body, up through her brain, into and through her blackened conduit, as it billowed forth in a dark cloud. Violet electricity arced between the two horns as the dark magic reached out to corrupt all that existed. That was something Twilight had wished she could fully control.

Sunset's own horn sparked to life to absorb the malignant mana. Almost immediately she could feel it clawing at her mind as it attempted to break through her mental barrier, and it continued to grow stronger until the unicorn was visibly fighting the darkness off from her soul.

Twilight immediately interrupted the flow. “Sunset!”

“Gods above, Twi. I only needed a little bit of the stuff.” She grunted in pain as the magic tried to leak out of her head, struggling to contain it. “I got it, though. Just sit back and -- urgh! -- relax.”

The mare did as told, but her eyes never left the unicorn. Even as she conjured up the framework Sunset was beginning to sweat attempting to resist the dark power now coating her horn. The setup was slow-going as she wrangled the magic to bend to her will, but her face eventually became one of complete concentration, and Twilight felt her own magic dancing across her body. Only then did she begin to relax.

Her eyes returned to the window, where the moon was now high in the sky. There, on its pale surface, was the Mare in the Moon. What appeared to be a cluster of dark patches in the shape of a pony head, looking down upon Equestria in its silent vigil, like always. That was her. That was the Dark Mare, glaring at her prize like a hungry wolf, impatiently awaiting her moment.

I can't allow myself to be defeated so easily, she chastised herself. Even if you refuse to associate with the rest of ponykind, you still have ones you do care about. They need the sun to grow their food, to be healthy, to be happy! And they deserve to be happy, don't they? And that is why you have to stop her!

But how?

Twilight felt her pony disguise slowly coalescing around her. She heard Sunset's grunt of effort at keeping the magic under control. She entertained, not for the first time, that she might have been wrong.

I hope Princess Celestia was right. I hope it really is just another ponytale...

Celestia hated it when she was right sometimes.

She stood on the top balcony of Ponyville's town hall and looked upon the moon. She had risen it, and then experimentally tried to move it to a different spot, but it refused to budge from its place in the sky. In her peripheral vision she could see the four cardinal stars beginning to move toward it. To release their mistress.

It was happening tonight.

She heaved a sigh that was equal parts relief and resignation. “At long last, it'll finally be over. One way or another...”

Her weary rosy eyes fell from the celestial body to the tree across the way. In there, Twilight and Sunset were having a gay old time (she hoped) with the townsponies. It was in their hooves now.

She whispered one final apology their way, and she disappeared in a gentle flash of light, never to be seen again until the dawn that she was uncertain would ever come.

Author's Notes:

Pinkie Pie; higher-res illustration

EDIT: Pinkie's chalkboard story~

Spicy isn't a flavor, for the record. It's a different sort of sensation that for the purposes of this story Twilight is capable of feeling. Along with the negative effects of alcohol, in large quantities. Don't really care if that makes sense scientifically; magic.

There was some significant problems with formatting when I first posted it, and it was embarrassing enough that I actually felt it needed another editing pass. And then another, because the image got broke. After this chapter, I will be far more careful with my editing.