Princess Luna was just beginning to awaken when something snagged at her burgeoning consciousness.

It was from Ponyville, again, and this disturbed her greatly. Over the last several moons she'd sensed, but was unable to find, the source of these strange disturbances in the peaceful nightly sleep of its residents. Her inner gaze cast outward, she focused her lunar lenses upon the small town which glimmered like the North Star for all the power it contained. Honestly, sometimes it was difficult to discern the dreams of mortal ponies for all the power that the Elements of... Elements...

One of the Elements was missing.

She gasped awake, sitting up in her royal bedroom decorated with constellations, black felt furnishings, and a responsibly sourced flask of red liquid upon her bedside table. She downed the entire thing in one massive gulp, and threw herself back under the covers. She would miss her morning appointment with her sister, and didn't have much time after that before the guards came to her room to check on her, but stars damn that mare something was going wrong in Ponyville!

It took the Princess of the Night an annoying 27.3 seconds to fall back into slumber, her anxieties eating through her carefully honed mantras and mental exercises designed to unlock that door within her mind that lead to the realm of dreams.

Again, she saw what should be the 6-pointed star of Ponyville gleaming like a lighthouse in a dark and tempestuous sea. Except the star had only 5 points, and the 6th had all but vanished. It was the blue point, the Element of... Generosity! Yes, that was it. Which one of them had been the generous one? The frilly one with all the hair?

Striding through the fading light of dreams, as stars winked out around her consumed by the growing light of the morning sun, she sought that sixth pony. Rarity had been her name. White coat, violet mane, blue gemstones on her-

Luna found what she was looking for. As the image of the pony became clear in her mind, the dream could not escape from her second sight. What she saw was, she remarked ruefully, a nightmare.

The sixth crystal shard of the elements was twisted, wrapped and warped in some kind of thick black vine. It pulsated and flexed, oozing an oily substance that smothered the thin blue light struggling weakly from within. The Princess dove in, determined to save what she could of this pony's mind. For though she had never seen the like of this before, she knew better than any what the dream of a dying mare should look like.

She appeared in a small wooden room, though oddly all the furniture was built to her size. Likely where the dream had begun, though the host would not remember it.

"Rarity!" she called, Royal Voice pounding upon the walls and shutters around her, "Attend your Princess, now!"

As the echoes of her own mighty voice reverberated, they slowly rippled outwards, and died. No response came.

Something prickled at the back of Luna's neck. An instinct honed over the course of her long, long life. This was a hunt. The room was too dark to be a dream, the candles and flames that normally adorned such spaces had all gone out, and the world outside of the small box windows was utterly black and void. A premonition haunted her that some beast stalked these halls, and that even she should be very, very careful.

Without a sound her hooves tread down the wooden corridor that was the only exit to the small wooden room, leaving the table and chairs behind. She noted a small teacup on the floor. Cracked, though nothing had spilled from it. The contents had all been drunk.

She heard a plaintive moan echo down the hallway in front of her. She could see nothing but the space immediately around her even with her superior night vision. Her hair stood on end, and she dimmed her billowing mane, eyes sharpening as she crept forward, straining to see any hint of the danger that she felt she knew awaited her.

The walls changed, fading away quickly to nothingness. From the wooden floor, stone grew. Cobbled flagstones like those of an ancient castle. She began to see corpses of brave knights and soldiers. Their eyes and mouths leaked a faint black smoke, their spears shattered on the ground beside them. She walked forward, ignoring the scent of death that hovered in the air about her. She came to a great wooden gate, blasted inward upon its hinges, and she realized that she must have been in a courtyard before, as she had lost sight of the stone walls around her. Beyond the gate was strange. The walls were not stone, but some kind of smooth black material. Obsidian? No, it didn't quite have the look of it.

The Night Princess snuck down through the gate. There were many halls, and many branches. This mare's mind had created a maze, a dark and terrible maze trying to keep out whatever malignance had wanted in. But it always went down. Down, down, beneath the bones of the mountains. Luna could feel the pressure of another's subconscious weighing on her. Most dreams happened just above the surface, but this one... this one had terrified the poor soul so much that it had sunk down into the black pit of unconsciousness.

Finally, excruciatingly, Luna came to the last door. Her heart pounded, sweat was slick upon her forehead, and a pounding sense of evil pervaded her own mind. This door was made of solid rock, with runes of ancient kind graven upon its every surface. Warding runes. "Keep out", they said, "turn back", but all the power had gone out of them, and they were merely words in stone.

Luna crept up to the door, and peeked one eye through. Beyond, she saw the horror.

A black, pulsing mass had filled a room about the size of the Royal Canterlot Library. Shelves of books, plants, and various potions had been smashed and overturned, before being consumed by the ooze. In the air hung a single light. A thin blue crystal, the Element of Generosity. Beneath it, suspended high in the air, was Rarity the Pony.

Her eyes, once sparkling, had become a dull grey, and thick black veins pulsed beneath their surface. She gasped and shuddered, her mouth leaking a thick, caustic substance from the corners. Her hind and forelegs were encased in what appeared to be the same substance, slick with an oily sheen. And her neck... sweet Celestia, her neck...

Luna swallowed hard as she gazed at the perverse tableau before her. Two thick tendrils of oil-black ooze slithered between the mare's plump thighs and buttocks. They pumped rhythmically, unceasingly, accompanied at every merciless thrust by a gushing of black liquid from the mare's open mouth, along with the sounds of a pitiful squeak of pleasure. Her muscles flexed weakly, and as they did more oil poured from the columns attached to the walls that held them suspended. Almost like a set of great wings, save for the fact that the thick, tuberous cables served only to bind the mare tighter in the creature's grasp.

Luna realized that she was staring, and her face flushed hotly as her stomach churned. What... what in Equestria's name was that thing? She sobbed quietly as she realized that, whatever it was, she was too late. Far, far too late to save anything that may have been left of Rarity. When she looked back through the door, a face looked back at her. And smiled.

Screaming, she ejected herself from the dream. Back out through the courtyard, through the wooden hallway, out into the void of dreamspace. Still the smile followed her. How that mare could smile she had no idea, and the thought of it made her mind reel with terror. She had to get out at once, had to warn Celestia and the others of the danger-

The six-pointed star was back.

Luna blinked, halfway out of sleep, so close to waking that she could hear the guards pounding on her door, demanding to know if anything was wrong.

The Elements of Harmony were whole again. Nothing was wrong, everything was as it should be.

Had it all really been nothing but a dream? Some mad whim of Rarity, its creator? What sort of sick pony would dream of such a terrible fate with such fervor that it could gutter the flame of Generosity?

Disturbed and deeply troubled, Luna allowed herself to wake. Though she feared that hauntingly brilliant smile would scar her for the rest of her days.

Author's Note

It's NNN, Happy Halloween :)