This chapter was heavly inspired by

Bluecolton's "A Sound In The Dark"

http://www.fimfiction.net/stories/relevance?search=A+sound+in+the+dark

Cover art that help inspired this chapter done by Koeskull

Princess Luna was just getting off of her chariot when she felt a sudden coldness she had not felt in a long time, not since her single night as Nightmare Moon. Recognizing the sensation, she headed inside Twilight's palace of friendship immediately and soon found herself in Twilight's bedchamber. Celestia was still holding onto Twilight, sobbing to herself. Getting closer to her sister, she heard Celestia whisper, “This is all my fault.”

“Celestia,” Luna began, causing her sister to look up through blurry, bloodshot eyes, “what happened? I can sense dark magic at work here.” Luna looked around, then back to her sister. “Is Twilight alright?”

Shaking her head, Celestia replied, “No, Luna, Twilight is not alright, and I fear the dark magic of Crystal Ridge has had a vile effect on her.” Gently laying Twilight’s head down on a pillow, Celestia could clearly see that Twilight’s face still showed no sign of recovery. Her eyes were still wide open, and drool was still slowly dripping from the left corner of her mouth. Luna looked at Twilight, then to her sister, saying gently to her, “Let me see if I can help her, sister. I might be able to bring her out of this.”

“Luna, don't. If you where to get hurt while you were in Twilight's mind, I don’t know what I would do.”

“Celestia, I am the princess of dreams. I will not get hurt. Now please, let me help.”

Luna’s horn glowed bright blue as her sister gently nuzzled Twilight's cheek. As Celestia's final tears fell, she said, “Don’t worry, my little Twilight. I won’t lose you again. Luna will take good care of you. You’re in good hooves with her.” Before Luna could say anything, Celestia got up and headed out of Twilight's bedchamber, leaving Luna to tend to Twilight alone.

Within Twilight's mind, Luna saw Twilight sleeping. Luna called out to her, “Twilight, you must awaken from this drea--”

Luna was cut off when she heard a dark, sick laughter coming from the farthest reaches of Twilight's mind. Luna watched as Twilight got up, hopped out of bed, stretched, then--completely ignoring Luna--headed into the library to see if Spike was attending to his chores. Reaching the library, she saw that it was completely empty, Twilight turned to head out of the library when she spotted Spike entering another room a few doors down from her location. Thinking Spike had forgotten to dust the books, Twilight walked towards the room Spike entered. Getting inside the room, she said, “Spike,” getting his attention. “Why aren't you in the library helping me clean?”

Spike turned around, took one look at Twilight, and ran out of the room screaming. Twilight blinked a few times, her head tilted to the right. With a confused look etched on her face, she muttered to herself while she ran after him, “What in the wide world of Equestria brought this on?”

Twilight continued to chase her little friend from room to room, all while Spike continued to scream and run away from her. Twilight chased Spike to a nearby room. As she entered the room, the scene shifted from her home in the crystal palace of friendship to Crystal Ridge. Looking around, Twilight muttered to herself as she began to walk forward, “Why am I at Crystal Ridge?”

“Twilight, you must awaken from this dream,” Luna called out to her. If Twilight heard her, she gave no indication. “Twilight, listen to me. You must awaken.”

Twilight looked around the old, derelict mansion. To her right were large stone pillars carved of the finest marble and jade stones. To her left were shelves upon shelves of books, beakers and other variables of science and occult magic. Luna could only watch as Twilight ignored her pleas. Twilight headed further into the mansion, muttering to herself, “Why I am back here?”

Twilight entered a door, and Luna followed. The scene shifted again. This time, Twilight found herself battling Sunset in her demon form. Again, Luna called out to her, “Twilight, you must awaken. Equestria needs you,” and again, Twilight ignored her pleas. “Twilight, that pony you're fighting isn’t real. Please, listen to me.”

Luna watched as Twilight rolled to the right, then to the left, while Sunset Shimmer fired wave after wave of green energy at her. Sunset quickly gained the upper hand, locking Twilight in an aura of green energy. Twilight screamed in pain as she could feel her bones snapping like twigs. Luna ran forward, only to have the scene shift again.

This time, she saw Twilight standing in front of a large pony with red and black patches where its skin use to be. It’s mane was knotted and filled with bugs. Where it once had eyes, now only two dead sockets remained. Its tongue flicked back and forth as drool dripped from its mouth. Luna watched in horror as the pony stepped towards Twilight. Twilight smiled, reaching out a hoof to it.

“Twilight, stay away from that creature,” Luna called to her, only to be ignored again. “Twilight, please, stay away.”

Twilight smiled, then began to laugh. Tears slowly poured out of her eyes, trickling down her cheeks. The skinless pony grinned a broken, toothy grin to Luna, who backed away from it. It opened its wings, allowing Luna to see the bones of the right wing and torn flesh of the left. Twilight slowly disappeared from sight as she merged with the skinless pony in front of her. To Luna’s shock, the two began to speak as one.

“What’s the matter, Princess Luna? Didn’t your sister tell you about my failure? This is what happens when you fail her: She leaves you like this.”

A voice from the dark caught Luna off guard. “Princess Luna, wake up.”

Luna woke up with a gasp. Looking around, she saw Spike standing next to a stallion. He was wearing a multicolored scarf and had an hourglass cutie mark on his flank. Bowing to her with Spike, he softly said, “My name is Dr. Whooves.” Dr. Whooves gestured to Spike with a hoof. “When Princess Celestia showed up with Twilight, Spike came into town and got me. I am the only pony that can save her. Please, let me help.”

“Is that why you've awakened me from Twilight's dreams? So that you can help Twilight?” Luna snarled out bitterly, causing the doctor to take a step back. “You could have done more harm than good, doctor. Now be off with you. I must return--”

“I beg your pardon, Your Highness,” Dr. Whooves began as he bowed very low to Luna, “but you must not go back into her mind.” Standing up, he took a step towards Twilight as he continued, with Luna being ever watchful of his movements. “I know what is happening to Twilight, and for you to go back into her mind now would only further what is happening to her.”

Luna took a quick look around, noticing her sister was not in the bedchamber with them. Spike tapped her on her left flank, saying to her gently, “Please, Princess Luna, let him help. He's the only doctor around in Ponyville.”

Looking from Spike to the stallion, who offered her a pleasant but sincere smile, Luna stepped back, saying as she locked eyes with Dr. Whooves, “Very well. If you can help her where I have so far failed, you may try.” Looking to Spike, she continued, “have you seen my sister, Spike?”

“Yes, Princess Luna. She's outside. She looks really upset. Let us help Twilight. You go help Princess Celestia.”

“Very well, but be careful. If what I saw within Twilight's mind was real, then she could very well be going insane.”

“We will, Your Highness, and thank you for letting Dr. Whooves help Twilight.”

Luna nodded to Spike and headed towards the front of Twilight's castle. She soon found herself outside, standing behind Celestia, who was weeping silently to herself. As Luna approached, she heard her sister say, “It’s all my fault. I never should've let this happen. Now I've lost her all over again.”

“Sister, you should know that Dr. Whooves is here. He seems to think that he can help Twilight.”

Celestia sniffed, wiping a hoof over her eyes, trying to dry her tears. Looking down and shuddering, she slowly looked up at Luna, her eyes bloodshot from crying. Luna gently wrapped her front legs around her older sister, saying to her softly, “It’s going to be alright, Celestia. I promise.”

Celestia sniffed again, replying, “No, Luna, it won't be alright. I am going to lose her.” Celestia ended the warm embrace. Turning her back on Luna, she opened her wings and took to the air, leaving Luna a bit confused. Unfurling her own wings, Luna also took to the air, giving chase to her sister.

The two flew for almost twenty minutes before Celestia banked low to the ground, landing a few feet from the train station. Luna followed suit, landing just behind her sister. Tucking her wings gently yet, tightly against her body, Luna said, “Sister, I don’t understand what you mean by 'I am going to lose her'. You acting very strangely towards Twilight. Such behavior is not appropriate for you to be displaying seeing as how she is you're student.”

Celestia didn’t reply right away. She looked at her reflection in a pane of glass in a nearby window of the building she and her sister had both landed in front of. Letting out a slight stilted sigh, she said, “There is something that I have kept from you since you came home, Luna. But once I tell you, I'm afraid you will hate me for it.”

“My sister, I will not hate you. I love you. All of Equestria loves--”

Celestia turned around narrowing her eyes to her sister. “I don’t deserve their loyalty or their love. Not after what I've done and allowed to happen.”

Celestia sighed, and she told her sister her true connection to Twilight, to Crystal Ridge, and to Sunset. Once finished, she saw that Luna had a look of pure shock etched onto her face.

Luna stammered on her words to her sister as she tried to make sense of what Celestia had told her, “Sh-She can’t be. Twilight is--and Sunset i-is--” Looking down, she continued, “This can’t be! Celestia, how could you?”

“I must go now to Crystal Ridge. You must remain here and look after Twilight. She will need you.” Turning away from her sister as the train could be heard coming into the station, Celestia continued, “Promise me one thing before I go, Luna.”

Luna looked up, her eyes still wide with shock and her face ghostly pale. “Y-Yes, sister?”

“Promise me that if I do not come back, Twilight will become the next to rule Equestria. She has a kind heart and a good sense of what is right and what is wrong. She will make a fine ruler, better than I have been.”

The train came, sounding its horn as it squealed to a stop. Celestia took a hold of her sister, whispering into her ear. “I love you, my sister. I will always love you.” Celestia boarded the train, leaving her sister at the station to weep silently to herself.

As the train slowly disappeared from sight, Luna turned to leave, but then turned around, unfurled her wings, and began to follow the train, saying to herself, “I love you, too, my sister. That is why I cannot allow you to go to that horrible place alone.”

Several hours later, Princess Celestia departed the train and flew the rest of the way to the mansion. Landing in front of it, she was about to enter the ominous building when she heard from above her, “Celestia, wait. I am going to help you.” Luna landed several feet from Celestia and the mansion.

Celestia looked over her shoulder to her sister. As she watched Luna approach her, she snarled out, “What in all of Equestria are you doing here, Luna? I asked you to stay back at Twilight's castle.”

“I know, sis--”

Luna was cut off when Celestia landed a clean, single right hook into Luna’s right temple, knocking her sister out with a single blow. As Luna collapsed to the snowy ground, Celestia whispered, “Forgive me, Luna, but I must face this darkness alone.” Celestia used her magic to gently carry her sister to a nearby pile of boulders. There, she laid her unconscious sister down onto the ground, clearing away any snow. She quickly searched the buildings for an old blanket and laid it on Luna to keep her warm. Her work finished, Celestia took one last look at her before entering the mansion.

The doors slammed shut behind her. Celestia turned to face the doors. Using her magic once more, she sealed herself in and shut Luna out. Turning back around, she proceeded to head deep into the bowels of the mansion, ignoring everything until she came to a crude lab. To her right were large cylinders filled with oozing, thick, green liquid. To her left were screens, papers and machines that she recalled seeing when Sunset had first come here seventeen years ago.

Looking over the cylinders, Celestia saw that each one had a number on them, ranging from one to twelve. All of them were broken, the glass shattered. Looking down, she saw the bones of infant pony bodies. The sight still sickened her as she recalled very vividly what was done to her own daughter at this place, what Sunset was, and what Sunset learned here.

Entering another room, she saw one more cylinder with "14" carved onto it. Looking around, she also saw where a second cylinder had crashed through a broken marble balcony overlooking a deep cliffside ridge. Celestia closed her eyes as she thought to herself, “I am so sorry I let this happen to you, Sunset.” Her thoughts were soon interrupted by a deep, feminine, and oddly echoed laughter coming from behind her. Spinning around quickly, Celestia came face-to-face with Queen Chrysalis, who smirked to her as she said, “Hello, Celestia. I am surprised you actually came back here again. Especially after what happened to Twilight and what happened here seventeen years ago.”