Celestia stood out on the balcony in Canterlot castle. The heat of the late summer day had faded, leaving behind a pleasantly cool evening. The sun was setting, and Celestia loved to spend the last waking moments of the day watching the beautiful rust-colored sun color the landscape with an orange hue before she lowered the sun enough to where Luna could raise the moon. This had been their cycle for centuries, and since Luna had returned from being Nightmare Moon, the cycle had resumed again. Sighing, Celestia aimed her horn at the sun and lowered slowly, feeling the temperature of the air drop as she did.

Celestia heard hoofsteps behind her. Luna, her mane flowing in the faint breeze stood there, full of energy to watch the night with. “Rest, sister,” Luna said as she stood by her sister’s side, “I will watch the night.” “I trust that you will,” Celestia said as she wrapped a wing over her little sister. Luna pointed her horn at the sky opposite the sun and lifted slowly. The fading rays of light from the sun dwindled to mere specks of light as the moon rose higher and higher. Celestia looked at the sky. “A crescent moon tonight, sister?” she asked. Luna nodded. “It has been quite some time since the last crescent moon, Celestia. I felt it was time for a change,” said Luna.

Celestia smiled weakly. Luna took note of this and asked, “Sister, you seem troubled. What is on your mind?” Celestia turned to walk into the castle. “You do not want to know, Luna,” Celestia replied gravely. Luna trotted over and stepped in her sister’s way. “Sister, if there is some danger to OUR subjects, I need to know!” Luna pleaded, adding as much emphasis on the word “our” as she could. Celestia placed a hoof on Luna’s shoulder. “Luna, I will tell you, since there is nopony that I trust more than you,” Celestia said with a sigh. She looked her sister in the eye. With a grave voice, Celestia said, “The Slenderpony has returned from its hiatus.”

Luna’s eyes widened as she took a step back. The shock and fear that came along with the words seeped through Luna’s skin like acid. The words burned into her brain, triggering terrible flashbacks. Her synapses froze; she could not think. Luna staggered back and moved out of Celestia’s way. Celestia looked at the horror on her sister’s face with an insurmountable amount of pity. She walked silently into the castle to leave her sister with her terrible and painful thoughts.

Luna lay curled in a fetal position for several hours, shivering. Her shoulders shook as she sobbed, silent tears spilling onto the cobblestone floor. Luna shook her head violently as the memories returned, as vibrant as if the events had occurred only the day before.

Luna was young, an Alicorn equivalent of a filly. She looked at her newly-acquired moon Cutie Mark with pride, feeling a sense of power. She was the night. She was powerful, even in her youth. Everyone would grow to love her as much as they loved her big sister Celestia.

Luna walked through the barren fields that would one day be the location of Ponyville. The long grass tickled her underbelly as she giggled and jumped through the breeze, soaring for short distances on her small wings, relying on the breeze to give her elevation. Luna laughed as children laugh when they are having fun doing nothing really at all. Tonight, she would attempt to raise the moon again, as she had done two days previous.

Luna soared into the Everfree forest. She tucked her wings in and dove, winding between the trees and avoiding stones. The Everfree forest was something completely new to the ponies of Equestria; it had barely been explored at all. While other ponies felt scared at the thought of entering the massive forest, Luna delighted in taking excursions into the woods. Even the mighty Celestia had her doubts about the security of the forest, and had often warned Luna not to venture alone into the forest until more of it was understood and chartered.

Luna landed softly on the ground. The soft, moist earth felt nice under her hooves as she walked further into the forest. She giggled to herself as she squished her hooves in the mud. Her laughter was startlingly loud against the nearly silent backdrop of the forest. Luna took note of this. She stopped and stood still, listening.

Every other time that she had come to the forest, it had been bustling with noises and sounds. Frogs croaking, insects buzzing, and animals shuffling around in the underbrush were sounds that had been abundant in Luna’s previous visits, yet all was silent now. Even the breeze had died down abruptly. Luna placed her hoof against a tree.

As her hoof touched the tree, Luna felt coldness. It was not the natural coldness of trees and plants, but the cold of dead flesh. Luna looked at the tree and realized that it was not a tree that she had placed her hoof against. She gasped and looked up in horror as the massive limb shrunk and became narrower. She saw other trees shrinking as well and turned to run.

Luna ran as fast as her small legs could carry her. She leapt over a fallen log, but her rear hoof caught against a broken branch, and she tripped. Luna gasped as her face slammed into the cold dirt, dirt filling her nose and mouth. She wiped off her face and rose shakily to her feet. The broken branch had cut her, and she was bleeding, but the cut was not serious.

A rock flew from nowhere at Luna, smashing into a nearby tree with force unlike any that Luna had ever seen. She shrieked and ran as she saw a massive figure stalking her, its outline just barely visible against the darkness of the trees. Luna screamed and took off, flapping her wings as fast as she could. She rose maybe ten feet off the ground and started flying as fast as she could.

She flew to the edge of the forest and flew into the sunlight. She ascended, flying well over fifty feet in the air. She felt the terror of the forest begin to leave has, even as the black tentacle wrapped itself around her rear leg.

Luna screamed as she was dragged forcibly down to around ten feet in the air. She struggled and thrashed, casting the few spells she knew. The tentacles dangled her, upside down, in front of the forest. Without warning, she was smashed into the ground with bone-cracking force. Luna screamed as she felt the bones in her left wing pop and crack as she hit the dirt. She was lifted up again and slammed into the dirt once more. Her head hit a rock this time, and Luna felt hot blood run down the side of her head.

Luna was dizzy as the tentacle threw her fifty feet away with enough force to create a groove in the dirt. Luna felt a bone in her leg crack, the pain in her body almost numbing. Blood ran down her face from multiple lacerations. Blood got into her right eye, and Luna wiped it away with her good hoof. She looked around, her vision shaky and ringed with white. In between flashes of black, Luna saw six or seven tentacles slither through the grass like snakes. Without warning, they darted forward and wrapped around Luna’s limbs and torso with a vise-like grip.

Luna barely felt herself lifted up high, around fifteen feet in the air. A figure emerged from the Everfree forest, the black tentacles emerging from its back. The being was very similar to a pony, except that it lacked hair and, for that matter, a face. No mouth, no eyes, no ears, nothing; just a blank white template of a pony’s face.

The creature lifted Luna close to its face, where Luna realized that her previous statement was partially wrong. The flesh where the creature’s mouth should have been expanded to nearly encompass the creature’s whole face. Luna saw many, many rows of razor sharp teeth and a bifurcated tongue as the head leaned in.

“Luna!” Celestia called as she hurled down from the sky. She hovered around a hundred feet in the air and shouted with as much power as she could, “Release my sister, monster, and prepare to face justice.” The creature hissed and its mouth rolled back into its head. Luna felt the tentacles slacken and she fell to the ground.

Celestia watched Luna fall to the ground. She immediately felt worried as she saw Luna crumple, but sighed in relief when she saw her sister’s chest rising and falling. She turned to see the creature staring at her. Celestia readied a spell.

Suddenly, a black tentacle wrapped around her horn, and another around her neck. The creature was looking her in the eye, its legs having stretched to an impossible length to be able to stare at her. Celestia felt the tentacle around her neck begin to tighten. The mouth that the creature had bared at Luna earlier had vanished, yet the creature spoke to Celestia mentally. In a voice that was utterly devoid of sex, the creature said, “I am far older than you are, meatsack. I know how you all work, how you cast your spells.”

Celestia felt the tentacle begin to choker her harder. Using all her strength, Celestia cast as powerful a spell as she could. The creature released her and staggered backwards. Celestia fell around twenty feet before she righted herself and flew to Luna.

The creature had beaten her there, though. Using its tentacles, it grabbed Luna and dragged her to face it. Luna felt her eyes being forced open, and found that she was staring face to face with this creature. It made no attempt to eat her as it had before. Instead they simply stared at each other.

Luna looked into Its eyes, and It looked into Luna’s. Luna felt her eyes widen and inside her head she saw terrible imaged of death and chaos and pain. The images felt like a brand being pressed to her brain, and she screamed.

It released Luna and watched her fall limp. It then turned and re-entered its home. It needed not to feed now, as it had done its job. The seeds of madness had been planted. It had decided that the small one would make for a much better madpony than her sister, since it would be extremely painful, emotionally, for the larger pony to deal with her sister. It preferred psychological torture over physical pain.

When Luna awoke in her bed at Canterlot after three days of steady nightmares. Celestia had been there to comfort her. “What was it?” Luna asked weakly. Celestia looked at her sister. “I have conversed with Ziz, Behemoth, and Leviathan. They all agree as to what it was, but all you need to know is that it is very old, very powerful, and that it is gone for now.”

“Will we go hunting for it?” Luna asked. Celestia shook her head. “If it does not want to be found, we will not find it.” said Celestia. She bowed her head and nuzzled her sister under her chin. “Now, rest,” she said. Luna felt her eyelids grow heavy, and sleep overcame her.

Millennia later, a more mature Luna still lived in fear of the creature that Celestia had dubbed the Slenderpony. The images of the mouth about to devour her, of the tentacles slamming her into the ground, and of the creature stretching its limbs like rubber had been engraved into her mind.

Worst of all were the images the Slenderpony had deposited into her head. Images of death and fires and mutilation. It was like looking at pictures of Hell. Luna shivered, despite the temperature being quite warm.

Elsewhere, It stood over a carcass of a small colt. The Rake gnawed on a deer bone nearby.