Twilight's hoofbeats echoed eerily as she followed Celestia into the darkness. The further down they went, the colder it became, and the more insufficient her purple light seemed. Even the princess's own sunbeam gave the illusion of fading as the ceiling above them soared, effectively burying them in shadow.
"What's down here?" the unicorn tried to ask. But her mouth was too dry. She swallowed and tried again.
"You'll see," Celestia said softly. She seemed to sense the feeling of something ancient and nowhere near equine down here, the same feeling that was making every hair in Twilight's coat stand straight up. Every step they descended was like another year taken off of her life.
"Maybe we should do this tomorrow," she croaked. Her heart was beating in her chest like a pegasus flying into the face of a storm, and her legs were trembling. Even the light from her horn was faltering, which scared her almost as much as the shadows closing in from all sides. Her magic hadn't failed her since she was a foal.
"It's alright, Twilight, there's nothing to be afraid of. We're almost to the bottom, see?"
Sure enough, they stepped off of the stairs and into a long, narrow hallway. The end wasn't visible, and a cold draft smelling of earth, decay, and...something sharper wafted towards them. Twilight squinted. What in Equestria was that smell?
"Put out your light," Celestia commanded, her voice still soft with something that may have been respect. She glanced at her, wondering if maybe her teacher was a few pages short of a full novel.
"But it's so-"
"Trust me, Twilight."
The princess had already extinguished her own glow, making Twilight's pitiful violet guttering the only light source. Taking a deep breath of the oddly-scented air and closing her eyes, she summoned Pinkie Pie again. Guffaw at the grossly...
Her light vanished. Expecting to see nothing but a wall of solid blackness in front of her, she opened her eyes. But instead, the passage was lit very faintly by watery, bluish light, almost like the kind that might be seen on a winter morning after the sunrise has faded but the sun itself is still hidden behind the mountains.
Teacher and student headed down the passage together. It was barely wide enough for them to walk side-by-side, and Celestia's folded wings frequently brushed against Twilight's flank. She was surprised at how...spiny they were. Almost as if the feathers were quills. She had always thought the princess's wings would be as soft as clouds to the touch, like those of a normal pegasus. But these were different.
"Now, this might be something of a shock to you..." Celestia began as they rounded a corner. Twilight was shaken out of her musings about wings with a cry of horror.
A huge chamber was set out in front of her. Almost dome-like in construction, the walls were completely covered in the skulls of ponies. Horns adorned the foreheads of the unicorns, wingbones framed the pegasi, and the earth ponies were terrible even without any ornamentation. One thousand empty eyes seemed trained on Twilight. One thousand vengeful ghosts seemed to walk towards her. And one thousand silenced voices seemed to scream in pain.
"This was here far before the palace was built," Celestia breathed, wrapping her student in one sharp wing to comfort her. "I've always wanted to get rid of it and make something else out of it, but I couldn't bear to bring anypony down here to see it..."
Twilight just nodded, her eyes fixed on the statue in the center of the room. An alicorn, with a skeletal horn, six insectine wings, and the stony corpses of ponies crushed beneath its hooves. Water trickled from its empty eyes, two mouths, and the gaping hole where the cutie mark used to be, leaving lines like black blood.
It was horrifying beyond belief. She had never known that such things existed in Equestria, much less in Canterlot, directly below the palace. But even as she trembled with shock and disgust, the scholar in her was musing at the superb craftsmanship of the pagan statue. She knew that in the dark times, after the three-way truce had faded, but before Celestia and Luna, before even the war, ponies had turned to dark gods for their daily needs. Creatures of the night, the black spaces between the stars, death. The ponies prayed for victory over their enemies, and prosperity for their families. They built shrines like this, and sacrificed unicorns, pegasi, and earth ponies alike to please their deities. But most of these places had been destroyed.
Raising her head, Twilight tentatively walked into the room. She was careful to avoid the trenches carved into the floor, not wanting to think about what they must have been used for. Grotesque as it was, this was quite an archaeological discovery. So much of pony culture had been destroyed after the advent of the alicorns. Most ponies were content to leave the fear and war in the darkness of the past, but it was a subject that had endlessly fascinated Twilight. Was this why Celestia had brought her down here? To study this place?
"Princess, do you realize how important this is?" she asked, glancing over her shoulder as Celestia followed her into the temple. "We need to get the archaeological team from the Royal Canterlot Institute down here. They'd have a hayday."
"Hmm, maybe you're right." The princess walked up to the statue, a thoughtful look on her face.
Twilight was examining the strange runes on the floor. She had never seen anything like them; were they an early form of magic, or perhaps the written form of a forgotten language? If only she hadn't left her notebook in her suitcase, which for all she knew was still in the carriage. She would have loved to copy these down. The idea of sitting in front of the fire in the library back in Ponyville, translating the runes with a cup of tea and her copy of "An Advanced Guide to Dead Languages" was simply heavenly. Twilight had always seen herself as more of a researcher than a field scientist.
It was then that she noticed the door.
Small and nondescript, it had obviously been designed not to be seen until somepony got right up next to it. Unable to resist her curiosity, Twilight trotted up to it and placed one hoof on it, ready to push it open. She glanced over her shoulder at Celestia, who was still frowning up at the creepy statue. She would expect her to explore, wouldn't she?
"Maybe this was where they kept the victims before the sacrifices," she whispered to herself. Repressing a shudder, she pushed open the door.
The first thing that hit her was the smell. Gagging, she backed away, throwing one hoof over her nose as her eyes watered. Rotting meat, feces, blood, urine, and that same sharp smell that had greeted her at the bottom of the stairs, except much, much stronger. The worshipers hadn't left somepony in here, had they? No, even if they had, after so long, the smell would have faded. This was something else.
Once again driven by her insatiable curiosity, Twilight entered the stinking corridor behind the door. Immediately, she saw what had to be the source of the vile smell. A trench ran along one wall, disappearing into a hole carved to look like the open mouth of a dragon. Perhaps there had once been water in it, but now, there was only black sludge, streaked with red in some areas. It wasn't moving at all.
"What is that?" Twilight whispered to herself, examining the stuff with disgust. Squashy red and pink things, dark, tangled stuff that looked like hair, an oddly-shaped green object that...was that a hoof?
Feeling sick, she backed away from the trough, trying not to inhale. Her haunches bumped against another doorway, but this one had no covering. Turning around, she peered into the room beyond and screamed.
"Celestia! Celestia! Help! Something-there's something-"
She clapped her forehooves over her mouth, no longer worried about shielding her nose. The smell couldn't compare to what was in that room.
She was going to be sick. No, she was going to faint. Most definitely. She couldn't handle this-
And yet still she kept her eyes fastened on it.
A pure black alicorn, stripped of her armor and with her eyes closed, lay on a table that seemed designed for butchery. Her head was resting limply in a drain. Her hooves were secured to the sides of the table by cruel black iron claws. Her wings had been nailed to the stone with tremendous force, leaving them twisted piles of broken bone and torn flesh. Her back had been brutally torn open, her ribs broken, a section of her spine shoved roughly to the side. And her lungs had been lifted from their cocoon within her chest cavity, held aloft in the foul air on the sharp points of the broken ribs.
But by far the most terrifying thing was the way that the lungs were still slowly inflating and deflating. By some miracle (or curse), this pony was still alive.
Twilight stumbled back, not daring to scream anymore. She didn't even dare to open her mouth. After almost stepping in the trench of black sludge, she whirled around-to come face to face with Celestia.
"Princess," she gasped. "There-there's something in there, Luna or Nightmare Moon, I don't know, but they-"
The princess reached out and gently stroked her, trying to calm her down.
"It's alright, Twilight. Shh."
"No! No it's not! Somepony did this to her, she's still alive, we have to get her out, hurry, she's hurt, she's hurt bad-"
"I know, Twilight, I know," Celestia murmured, her gaze straying to the room that Nightmare Moon was in. "Awful little creature. She just couldn't mind her own business."
A/N: I warned you, didn't I? I know that the "omg Celestia's evil!1!one!" thing has been done before, but I wanted to bring something new to that particular table.
As for the fanon in this chapter, it pretty much explains itself, except for one thing. I believe that Nightmare Moon is almost like a defense mechanism for Luna. She's bigger and stronger than her, and more heavily armored. Maybe the princess of the night changes into her whenever she feels threatened?
One more thing. This is actually the last chapter I wrote, and I wrote it almost three months ago. So now I have to get off my lazy ass and actually write a new chapter-if people actually like this, that is. Review, please. And I'd appreciate it if there were no "My god, you should be ashamed of yourself, this is a children's show" comments. I realize that, and believe me, if your younger siblings stumbled upon this, I am so sorry. I never wanted any young kids to be scarred by this. But if they were on this part of the internet, you probably should have been supervising them.