Cease this at once...SuBmIt!
Dreams are meant to be havens of the mind, sancuaries of all hopes and wonders. But there is a darker side of dreams, a realm of horror and pain; the realm of nightmares. Princess Luna, Alicorn of the Night and Mistress of dreams has always helped the ponies of Equestria; helping them overcome their fears and gaining new confidence. But even she holds fears, even Luna can have nightmares. For years now, the dreams have been the same; Luna can see somepony off in the distance; just out of reach. She goes to see who it is, only to find a blackness swallowing her up.
"I'm telling you, this is too strange!" Luna objected as she spoke to her sister. At first, Luna held the dreams back. But as they grew worse, she had to tell somepony. So, she turned to her sister, Princess Celestia, Alicorn of the Sun and Maiden of the day. "There must be a message, or reason for these nightmares."
"Luna, Luna, Luna." Celestia scoffed, her body resting upon her throne. Though the two were equal in power, and both held their own thrones besides the other, over the years, Luna felt Celestia becoming too full of herself. "These nightmares are probably a normal thing, even alicorns such as us can have them."
"But after years of the same dream?!" Luna protested, her voice echoing through the throne room. "How is that-"
"Hush sister!" Celestia replied, raising her voice like a scolding mother. "The more you worry, the more it may occur. Put it out of your mind. I have too many delegates and not enough time for my sister's dreams."
"You don't ever have enough time for your own sister." Luna mumbled to herself as she turned, leaving the room.
Later that night, when Luna's work was complete, her dreams were warped into the hellish nightmares. This night was even worse than before. Instead of the darkness that she was struck with, Luna met this black figure. It was a twisted perversion of herself; black and evil. Luna found herself frozen with terror as she stared into the empty eyes of this creature. Luna tried to flee, to wake up, anything, but she was unable to move. The nightmare Luna tilted her head and smiled. Suddenly, long and thick barbed wire sprang from the very air, wrapping around Luna's body; binding and stabbing at her. Luna screamed in agony and pain. The barbs tore at hair and flesh, crimson blood dripped and ran like thin lines over the wire. The nightmare only looked on and stared at Luna, silent yet it mocked and laughed at her pain. More and more wire wrapped around her, tearing into her arms, legs, wings, face, and neck.
"W-what do you want from me?" Luna cried, tears mixing with the blood on her face. "Why do you torture me?"
"...ToRtUrE,,,?" The nightmare asked, tilting her head the other way, the sickening smile still on her face. Her voice was dark, yet held almost a small similarity. It was as if the creature held both Luna's voice, and another voice. "...yOu...ToRtUrE...yOuRsElF..."
"What?!" Luna called back, more shocked at the sound of the creature's voice. As she asked, the wire tugged at her more, increasing the pain. "What do you mean?"
"...yOu...HiDe...In...ShAdOw...UnDeR...hEr..." The nightmare answered, her tone sounding as though she took delight in Luna's pain. "...ShE...mUsT...dIe..."
"What?! Who?" Luna asked, trying to get answers, though the pain only increased. "Who are you talking about?"
"...ThE...oNe...WhO...hOlDs...YoU...bAcK..." The nightmare's smile was now a hideous and twisted expression of sadism and delight. "...cElEsTiA..."
Luna could see the murderous intent in the nightmare's empty eyes, she wanted Celestia to die. But why? Luna tried to speak up again, to ask, but she could see the nightmare no longer wanted to talk; only to further torture her. At that realization, the wire pulled harder than it had before, tearing and digging into Luna's body, eventually pulling her apart. Luna let out a final screeching scream as she was ripped apart. Blood splattered, her entrails and organs hung from her torn body, and her limbs merely dangled in the endless darkness.
Luna's eyes burst open, finding herself away and in a cold sweat. Looking around the room, Luna saw no nightmare figure, nor did she find any markings of the barbed wire. Though despite it being a dream, Luna's chest nearly burst from the pain she felt. Jumping from her bed, Luna raced down the halls; she had to see that Celestia was alright, this nightmare could not wait until morning. But just as she reached Celestia's door, Luna stopped. For some reason, her mind raced back to what the nightmare had told her. Was Celestia really holding her back?
"No, it can't be." Luna quietly told herself, pacing a little in front of the grand door. "She's my sister, I know she can be harsh, but she loves me, I know this. But why...why does it feel like she brushes me aside like some inconvenience?"
Luna again approached the door, but her fear stopped her again. She couldn't even bring her hoof to gently touch the door. Sorrow gripped the mare's heart as she turned and slowly made her way back to her chambers. As she brooded her way back to her room, she failed to notice the nightmare, smiling from within her shadow. She would have Luna for her own, one way or the other; no matter how long she had to torture and corrupt her.