When Nightmare Moon fell to the Elements of Harmony, every pony believed the vile mare had forever been defeated. However, none knew that in all her time on the moon, she had been planning not just her escape, but her return if she were to fall. Were the Elements to strike her down once more, she would use all her strength to escape her alicorn host and become little more than mere energy. Slowly, she would gather power and, like the phoenix, be reborn.
All about Equestria, Nightmare's dark energy littered the air. Invisible to the naked eye, no pony saw, smelled, or even felt the terrible essence floating about their homes. It nudged and scraped against every wall, stone, and cloud; biding its time. Waiting for its time to merge and become the terror of the planet once more.
Up high in Canterlot, the wind jubilantly tossed the leaves about into a colorful dance of reds and oranges. Tri-colored hair partnered itself with the leaves in their bountiful dance. Celestia smiled while her swaying mane blew about in its own direction, ignoring the wind completely. Beside her a lavender unicorn smiled back to the tall pony..
"I'm glad you came to Canterlot to visit, Twilight. I always enjoy our meetings."
"Thank you Princess." Twilight happily answered back, tearing her eyes away from the rich colors that laced the Canterlot Castle gardens.
"Yes! We do most enjoy thine visits Twilight Sparkle!" hollered Luna, the recently re-established princess of the night.
Purple hair shot back in the wake of Luna's powerful lungs, unable to stand up to the princess's cry. Twilight forced another smile as Luna blew a wall of wind into her face, which smelled oddly of garlic and peppermint. After her gums finished flapping from the force of Luna's voice, Twilight spoke.
"I enjoy the-" Twilight paused to let the world stop spinning. For a second, she swore she saw Pinkie with green face paint and a long snout, riding a broomstick, and cackling about a wizard and munchkins. "I enjoy the visit's too, Princess Luna." she replied, her eyes still softly twirling in their sockets.
"Tell us Twilight Sparkle! How goes the friendship quest!?" Luna released a windstorm in every word. Around them, the statues shook and windows wobbled lightly under her gale force voice.
Librarian legs were not meant to go against winds rivaling those of hurricanes. As such, Twilight skid back ten inches on the hard cobblestone path before flipping over completely. Not wanting to embarrass herself in front of her mentor, Twilight quickly rose back to her hooves and responded to the mare of the night.
"Well, it's been pretty quiet lately. I think the most that has happened is Pinkie argued with Applejack about whether boots are for eating or not."
"Why, that is preposterous." Luna cried, careful to keep her voice at tolerable levels.
"I know. Pinkie swore they were for boiling and eating." Twilight responded with a light chuckle.
"One does not simply boil a boot!" The princess of the night declared.
"That's what I tried to tell h-"
"Boots must be marinated then rolled in bread crumbs!" Luna decreed.
"What?"
"It's a long story Twilight. We had a hard winter one year when we were fillies." Celestia told her pupil. The warm smile she wore never once left the white mare's face. Twilight nodded back at her teacher, accepting Celestia's explanation and not questioning the matter any further.
For a moment, Twilight stood still, her eyes locked of the gentle push and pull of the plants around her. Her mind's gears began to grind away for the thousandth time that day. Fillies, whenever Twilight imagined the princesses, she always envisioned them as they were now; tall, majestic, and powerful. It never crossed her mind that they too were ponies and had a fillyhood. She wondered what creatures such as them could possibly have been like as children. Who took care of them, and what it was like to care for an alicorn?
Twilight opened her mouth for inquire into this when several glows came to life in mid-air. Both princesses raised a brow at the sudden phantom glows. Immediately more appeared, then more and more, each emanating a faint purple light. Slowly the purple glows came together into a bundle. Grey soaked into the vegetation surrounding the hovering glowing sphere. Small pieces of greenery below it withered and died instantly.
"W-what's going on?" Twilight stuttered.
Neither Princess Luna nor Princess Celestia had an answer for the frightened mare. Despite their own worry, the pair kept stoic faces and lit up their horns in preparation for whatever would come from the glowing sphere.
Surges of electricity sparked and shot out from the light-emitting ball, freezing anything they touched. The purple sphere turned a dark shade and descended to the ground. Grey cobblestone cracked and shifted in its presence. Directly under it the ground turned a sickly violet, humming and glowing to the rhythm of a heart. The sphere exploded in a flash of light and familiar laughter filled the air.
Smoke bellowed from the ground the sphere exploded over. In place of the glowing ball was a pitch black pony, adorned in blue armor and purple eye shadow. She released a malevolent smile. Celestia, Twilight, And Luna could only gape in shock at the sight.
"Remember this day you foals, for it is your last. Now the night. Will last. Forever!" she cackled. A blaze of blue sparked from her horn and quickly grew to envelop the entire length.
---
In the castle, a unicorn known as Penstrokes Scribe continued work on his novel. It would be a wondrous tale of a evil creature once banished returning to life with no memories of its past. Only through the kind love of a librarian pony would it defeat its inner evil. Just as he came to climax where the beast was taken away from its caretaker, the candle beside the stallion went out.
"What the?" he asked himself. Shrugging, he magically thumbed around the drawer below him. A red match floated up out of the desk then struck a piece of sandpaper beside him. Immediately he relit his candle and continued his tale.
---
Nightmare's head made a slow tilt. Her reptilian eyes scanned the still very bright world around her in search for a star in the sky or a patch of darkness on the ground.
"What just happened?" she asked before gazing upon a massive white alicorn. "What the hay!? When did you become a giant!?" she screamed at Celestia. Seconds later a magical force yanked the black alicorn into the air.
Small legs thrashed at the yellow aura keeping Nightmare's body hoisted in the air. The dark goddess's horn lit up in a deep blue glow in her attempt at wringing the white alicorn's neck. Instead of a magical noose, the black pony received the equivalent of gently tossing a small pebble in Celestia's face.
"This is Nightmare Moon?" Twilight asked.
"We highly doubt it. Who art thou! And how did'st thou create thine ball of light!?" Luna asked, managing to push Nightmare back a couple of inches with her voice.
"I am the true princess of the night! I am Nightmare Moon!" The pony replied with a smirk, despite the golden aura that clung to her body and imprisoned her within the air. "Now die!"
---
Deep blue energy seeped out from the pitch black pony's horn again. Magical aura illuminated a small spot of her golden prison, but was quickly pushed back by Celestia's power. Back in the castle, Penstrokes Scribe continued to write what would surely be his masterpiece. The flickering flame beside him became shrouded and in a deep black, then died.
"Oh come on..."
---
"What - what was that?! That was supposed to smother you in darkness." Nightmare uttered in pure disbelief.
"Princess Celestia. Why is she a filly?" Twilight asked.
"I'm not sure." Celestia stated calmly as she brought the black foal closer to her face. Her eyes scanned over the small form of Nightmare Moon. Everything about the foal indicated it was in fact the Mare in the Moon, just a smaller version of her.
"Filly!? How dare you!" Arcane power flowed into the filly's horn, resulting in a few magic sparks flying out.
The young body of the dark alicorn pushed hard against her magical prison. Her muscles stretched as far as they would go in her attempt to break free of her restraints. Celestia's magical hold proved far superior to the child alicorn's physical strength, wearing her down in less than a minute.
"We believe the child's age doth have something to do with her lack of magical prowess." Luna said while she delivered a hard glare onto the filly.
Celestia nodded.
Nightmare's eyes locked firmly on the glasslike form of a pond. A small black filly in sky blue armor met her gaze. Altogether, the alicorn ceased breathing and her heart skipped a beat or two. She failed to find the words to properly express her feelings at the realization the filly staring back at her was herself.
"Twilight, would you like to accompany Luna and I to the royal laboratories? I'm going to run a few tests on the child to see if she really could be Nightmare Moon."
If there were a list of subjects Twilight loved the most, it would go Celestia/her parents, books, and science; in that order. Lavender ears perked up immediately at the mention of science. Giddy joy quickly welled up in the studious mare's heart, prompting her to shake her head vertically fast enough to produce a faint buzz in the air.
Celestia smiled once more in response and ushered her student to her, then trotted off into the royal laboratories. There, many tests were administered to the black alicorn. Being a kind mare at heart, Celestia refused any of the more gruesome tests but still allowed a few pokes and prods to the foal.
Luna secretly enjoyed the tests that inflicted any amount of pain on the child. She would momentarily feel bad for her amusement at another's suffering, but then she remembered this creature was most likely Nightmare Moon and the guilt lessened. Nightmare yelped once or twice when they needed to draw blood, but the remainder of the tests proved harmless.
After many tests the filly was proven to Nightmare Moon. Minutes after, the armored child found herself dragged into the throne room. Celestia's arcane grip on her tightened enough to release a audible "pop" from a few of the alicorn's joints. Yellow magic made way for magenta when Celestia handed the villain off to Twilight for holding.
The sisters strode forward five feet and turned to face the criminal.
"What shall we do with her? Banish the criminal back to the moon?" Luna inquired toward her elder sibling. Nightmare's eyes widened to the size of plates, while her pupils dropped to the width of a gnat.
"We don't have that power anymore, Luna. I don't think she would survive on the moon either."
"We do not see that to be an issue, dear sister."
"Luna! We aren't going to kill anypony!" Celestia shouted.
"Forgive us Tia. We merely harbor a intense dislike for the Nightmare." Luna scanned the hovering child with her eyes, noting the sweat rolling down the filly's sides. Hot, heavy breaths reached from the eldritch foal's mouth, all the way to Luna's ears where they pounded against her eardrums like oars against the ocean waves. Acting as counterpoint to Nightmare's horror, Twilight stood perfectly still in wait for the Princesses to make their judgment call. Luna smiled at Twilight's patience. "We - er. I," she said, finally correcting her linguistic era. "believe I have a solution."
"Oh?" Celestia asked. Twilight leaned in with anticipation. Nightmare cowered in fear, sure she was going to die a painful death.
"Nightmare Moon. For your crimes against Equestria. You will be sentenced," Twilight leaned in further and Nightmare felt her heart crash against her ribs in her chest. "to learn the magic of friendship alongside Twilight Sparkle."
"What!?" both Twilight and Nightmare yelled.