"The night will last forever!"
Nightmare Moon's maniacal cackling was interrupted by the double doors to the Ponyville Town Hall being blasted open. Everypony fell silent, now turning to face the unicorn in dark blue armor that was trotting in slowly and heavily. His mutated leg had three talons that held a deep red and blue cored crystalline greatsword the size of a pony with almost no problem. There was nothing else of the wearer visible except two glowing red eyes. A long red mane draped from his helmet. This unicorn seemed to have an air of hatred and darkness following him.
"What is this?" the dark alicorn asked, curiously watching this strange pony.
The unicorn seemingly responded by cutting a purple-maned unicorn standing right next to him horizontally in half, spilling her blood across himself and the floor. Naturally, panic ensued; everypony screamed in utter fear and fled through the double doors. Nightmare Moon's expression changed from amusement to absolute horror as the azure knight below slashed furiously at the fleeing ponies, killing them in half-dozens with each swipe of his gigantic sword and cackling with a metallic-sounding voice.
Despite wanting to torture ponies with everlasting night, Nightmare Moon wasn't planning on killing them. She disappeared into mist and reappeared on ground level. She blasted the azure knight with enough magic to incinerate flesh. The knight was blown to the ground, and his sword dropped to the floor with a very loud clang.
But that momentary defeat only lasted long enough to allow the ponies to escape. The stallion groaned and visibly glowed as it got back up to fight again. The knight used his left hoof to pick up his sword and glared at Nightmare Moon; his red eyes seethed nothing but fury.
"Name thyself, foul beast!" Nightmare Moon shouted.
Ignoring the question, the knight lunged at her.
Luna remembered very little about her foalhood by now; it all seemed twisted and corrupted when she thought back. As her memory shaped itself around tragedy, the only glimpses of her past she remembered with any clarity were torturous ones that either had her or somepony else once dear to her grievously injured.
And she remembered, with absolute, unwavering vigilance, her encounter with Nightmare.
It was before her and Celestia took on Discord, and it wasn't long after they had taken their seat as princesses. They were still young and only just beginning exhibit features of their alicornhood. Tia had grown fast, having a thinner frame and a mane and tail that was growing more colors. Luna was still growing into a taller body and a larger horn and wings.
The Nightmare they encountered was a dark knight once belonging to Luna's Lunar Guard. He was known as Noble Shadow, and both Tia and Luna believed he had died nearly a year ago in the crypt that held Soul Edge. However, his destroyed body was changed by the dark sword's power and taken over by its will. His right leg had become a demonic and wicked thing with five clawed digits. His right wing had become like the leg on the same side and lacked feathers, having become little more than a functional bone limb in both appearance and use.
Tia and Luna were both at Nightmare's mercy, having been nearly killed in the fight to defeat and restore him. The power of Soul Edge had proven more than a match for their Light magic. The demonic thing was like a gigantic butcher's knife with flesh filling the blunt side of it and a single, bloodshot eye at the base of the hilt. Nightmare, though less armored than his opponents, was surprisingly nimble with the greatsword in hoof and able to dodge the mostly magic-based attacks the princesses threw at him. He did not escape unscathed, however; his chest leaked dark blood from a slash across his ribcage.
Luna, laying weakly by Nightmare's hooves, heard a sound in her head. A drumbeat, a simple ba-ba-ba-bum that paused before looping. Was it her heartbeat? Alicorns had two hearts, after all. No, it sounded different. It was louder, growing in her mind, compelling her to act. She had to act!
Luna sprang up and grabbed Soul Edge by the hilt, struggling with Nightmare over the blade. Pure anger and tenacity alone allowed her to grab the blade from him and thrust it through his chest. The eye on Soul Edge stared at its new wielder, pleased at the immediate violence. Luna, endowed with new strength by the sword, lifted Nightmare up to his hind hooves and cut him vertically in half, bathing herself in his blood.
The two halves of Nightmare fell to their respective sides, a fraction of a smile plastered on both sides of his face.
Nightmare Moon had barely a moment to dodge Nightmare's attack. She blasted him again, but it didn't even faze him this time. Shocked, she hit him with a constant stream of her magic, which was only enough to slow him down. He trudged forward slowly, Soul Edge raised and swung.
Nightmare Moon let out a cry of agony; Nightmare had cut her left wing in half. She lost her focus and her magic stopped. Nightmare kicked her to the ground, chuckling.
"Burn!" he screamed as he again raised Soul Edge, this time to kill. Nightmare Moon closed her eyes, bracing herself for death.
A beam of bright white magic hit Nightmare, throwing him forward in a scorched heap. The source of the attack was Princess Celestia, standing tall by the body of the purple unicorn. Nightmare Moon could see light reflecting off the tears in her eyes. Nightmare tried to rise again, but Celestia blasted him once more, this time with the untempered power of the Sun. His azure armored body was incinerated into a contorted ashen husk, but Soul Edge was unscathed.
Nightmare Moon's body, out of newfound remorse for her sister and fear from what she believed was her death, changed back into her normal self: Princess Luna. Luna was weak and still retained the injured wing. She rose shakily, staring at her sister, and galloped to her side.
"Sister! You... you..."
Princess Celestia nodded solemnly and then knelt down by the unicorn, who lay dying on the floor. She had clung to life, even despite her mortal wound. Luna watched uncertainly, trying hard to both ignore her injured wing and find a connection between her sister and the dying mare.
"P-Princess..." the mare groaned, in shock from blood loss.
"I'm here, Twilight," Celestia said calmly, her voice still confident.
"I... I failed you, Princess. I'm... so sorry..." She coughed up some of her own blood. "Please for... forgive me."
"You didn't fail me, Twilight. You were brilliant. Absolutely brilliant. It was I who was foolish. I did not see the signs, and now..." Her voice faltered. "But you were right. You were absolutely right, Twilight; I should've paid attention."
For a moment, Twilight stared blankly off, and both sisters thought that she was dead until she took a shaking breath and lifted her head meekly to speak. "It... it hurts... so badly. M-make it s-s-stop, Princess... please."
"I will," Celestia said, her voice suddenly shaking. "Twilight."
Celestia's horn glowed, and Twilight's breathing came to a halt mid-breath. Her head fell back to the floor, and the unicorn had passed on. Celestia closed Twilight's eyes with her hoof, and then she turned to Luna, her tears now falling down her off-white face. She moved forward, embracing her sister, and cried softly into her shoulder.
