Rarity's eyes snapped open. It had all been a dream. Sweetie Belle had not found out about her secret life. She was still an innocent filly, blissfully unaware of what her sister really was.
And yet she was still screaming.
Rarity looked at her surroundings and she was still standing on the basement stairs. Sweetie Belle was still looking into her basement in horror at what she was seeing. She was still screaming. She wouldn't stop screaming. The screams reverberated through her house. It filled the very air and bounced around in Rarity's skull to the point where Rarity was sure that it would leave a permanent scar in her mind. She grunted and shakily reached a hoof up to cover one of her ears.
Rarity's eyes snapped open. It really had all been a dream. Sweetie Belle had not found out about her secret life. She was still just an innocent filly, blissfully unaware of who her sister really was. But somepony was still screaming. Sweetie Belle. Sweetie Belle was screaming. Rarity squealed and bolted down the stairs and scooped up her screaming sister. She placed Sweetie Bell on her back and ran up the stairs, slamming the basement door behind her. Sweetie Belle stopped her screaming when they exited the basement, but she began hyperventilating. Rarity ran Sweetie Belle up to her room, and gently moved her from her back to the bed. She used her magic to pull the covers over her sister and tuck her in tightly. The filly whimpered, but stopped sobbing.
Rarity kissed Sweetie Belle's shaking head and gently stroked her mane. "I... I'm so sorry, Sweetie Belle."
Her sister didn't respond, so Rarity kissed her on the head and trudged out of the room. She shut the door behind her and went down to her workroom. She could think better there.
Rarity stopped just as she reached the bottom of the steps and leaned against the wall. She wiped her eyes and thunked her head against the door frame to her workroom.
"You really are evil, aren't you, Rarity?" she growled.
Rarity squeezed her eyes shut and choked back a sob. "I could have stopped her," she whispered. "I... I could have done more to protect her."
"She was having such a wonderful day before you ruined it." A snarl crossed Rarity's face, and she slammed her hoof on the ground. "She had just made two friends. She was so happy and you destroyed that happiness when she found out that you're a... a..." Rarity groaned and flattened her ears. Her gaze trailed to the ground and she thunked her head against the wall once more. "I don't suppose that they really have a name for what I am, do they?" she muttered. "Monster doesn't quite seem to do it justice."
Rarity reached her workroom, and her eyes scanned the room, looking for something to do, something that could occupy meaningless time until she could figure out what to do next. Her eyes landed on a half-finished dress that was draped over one of her mannequins. It would do. She blinked tears out of her eyes, summoned the half finished dress and sewing materials over to her and got to work.
A few hours went by before anything happened. Rarity was sewing a pattern on her dress when she heard quiet steps coming down the stairs. She perked her ears up and turned off her sewing machine just in time to hear Sweetie Belle's timid voice behind her.
Rarity turned around and almost had to hold back a sob at the sight of her sister. Sweetie Belle's eyes were bloodshot and her mane was unkempt. To cap the image off, her legs were shaking as if an earthquake was going through the house and she looked like she hadn't slept in years.
Rarity put on her best brave face and stood up from her stool. "Oh. Hello, Sweetie Belle. How... how are you?"
Sweetie Belle leaned against the door frame, her eyes trailing to the floor. "I don't know." She took a deep breath and her gaze moved up to Rarity. "What did I see down there?"
"Well, I don't know. What did you see down there? Tell me and I'll do my best to explain."
Sweetie Belle bit her lip and closed her eyes to visualize what she had seen. "Well... I saw a table, a lot of what I think was dried blood, uh, pony skins and manes on the wall, something with feathers and, uh, hooves maybe?"
"That's about the extent of it really," Rarity admitted.
"What does it mean?" she asked. "I get the blood, but what was with the skins?"
Rarity cleared her throat and put her sewing materials back in their case. "Well, if a pony that I... you know... has a hide or a mane that I particularly like, I put them on my wall."
"Oh," Sweetie Belle muttered.
"What are you thinking right now?" asked Rarity. Sweetie Belle shrugged. "That's all; you don't know?"
Sweetie Belle turned her head and looked in the direction of the basement door. "Well, I guess I want to see the basement again now that I know what's down there."
Rarity's eyes widened and she took a step towards her sister. "Oh Sweetie Belle, I don't think that is a very good—"
Sweetie Belle turned back to her sister and fixed her with a glare. She stomped a hoof on the ground. "I practically live here when Mom and Dad are gone! I know how to get in anyway; I'll do it whether you want me to or not!"
"Sweetie Belle, that's not a world that I want you to be a part of!" Rarity took a step forward, extending her hoof towards her sister. "I don't want you seeing that part of me! Please don't go down there!"
"I've already seen it!" said Sweetie Belle. "I just..." The fire drained out of Sweetie Belle, and she lowered her head and drooped her ears. "I don't know, I think I'll feel less scared if I can see it already knowing what's down there."
"Sweetie Belle, that doesn't—"
"I'd rather go down with you," she said.
Rarity's eyebrow raised and she cocked her head. "Even though you know I caused all of it?"
Sweetie Belle nodded. "It makes me feel bad because I don't understand. I need to know."
Rarity sighed and she turned her head to the basement. "If you really are sure about this..."
"Yeah. I am."
Rarity slowly began walking towards the basement door. "Follow me."
The trip down to the basement was far less eventful than their previous one. Sweetie Belle seemed nervous as they walked down the stairs, but she still had the determination to understand that she had when she had come down here last time. As they walked in to the main room, Sweetie Belle's eyes widened with fear as she got a good look at the carnage inside. "We can leave whenever you want to Sweetie Belle," said Rarity.
Sweetie Belle merely nodded. The next few minutes seemed like an eternity to Rarity as she watched Sweetie Belle explore her dark world. She read her poster, examined the skins and manes on the wall, and she even managed to find her large collection of knives. "Anypony I know here?" she asked when she examined the wall of skins.
Rarity pointed to the paint splattered pelt. "That one is Trixie, the boastful unicorn who came to town a while ago. The one with feathers is Gilda, Rainbow Dash's friend."
Sweetie Belle nodded. She examined the wall for a few more moments and ran her hoof over a blank spot on the wall. "Can we put Diamond Tiara's skin here?"
Rarity's eyes widened and she moved Sweetie Belle away from the wall. She planted herself firmly between the two. "No! I don't kill foals!"
Sweetie Belle's glare returned. "But you killed those bullies when you were a filly!"
"Yes I did, Sweetie Belle, but I was a filly myself back then. I haven't killed a foal since I was eleven years old and I promised myself I wouldn't do it again!" Sweetie Belle continued to glare at her. Rarity groaned and facehooved. "Look, Sweetie Belle, I cannot escape my actions. I've killed countless ponies and I can never take those deaths back! You don't have to be like me!"
Sweetie Belle's glare faded and her ears flattened. "But... but I've always wanted to be like you," she whimpered. "I was always proud to have you as my big sister."
"Something I never deserved; then or now," Rarity insisted.
Sweetie Belle's muzzle was nearly touching the ground and she would have hidden in her mane if she could. "What do you want me to do now?"
"I want you to go back upstairs and do your best to forget that this ever happened." Rarity placed a gentle hoof on Sweetie Belle's shoulder. "Push the angry feelings out of your mind, and don't be like me."
Sweetie Belle looked up at Rarity angrily, tears forming in her eyes. "You know I can't ever forget this! Let me help you once or I'll tell!"
Now it was Rarity whose eyes fired up into a glare. "You Pinkie Promised, Sweetie Belle! Do you know what happens to ponies that break Pinkie Promises?"
"What? What do you do?" asked Sweetie Belle, her anger rising with Rarity's.
Without thinking, Rarity pointed at one of the hides on the wall. Sweetie Belle's anger faded away and she shrank back.
"If I tell, you'll do that to me?"
Rarity let out a small gasp and flattened her ears. "No! Sweetie Belle, if you told the entire kingdom of Equestria what I do down here I still wouldn't hurt you at all! I made a promise to never hurt you and that promise remains!"
Sweetie Belle straightened up slightly. "Well, then what now? I'm not forgetting that this happened; that's impossible for me to do. I can never look at you the same way now!" Sweetie Belle's glare returned. "I have angry feelings too, you know. I've imagined myself hurting Diamond Tiara. I can help you do this!"
"There is a huge difference between imagining it and actually doing it, Sweetie Belle," Rarity insisted. "Everypony has imagined what it would be like to hurt another pony, but the actual action is something far different. You would never be the same."
"You don't seem to be too sad about it!" said Sweetie Belle. "Do you ever feel bad about what you do?"
"Yes, I most certainly do!" Rarity lied. She sighed and looked around her basement, her eyes scanning the various pony parts that adorned it. "I wish that I could go back to the day when I first killed those bullies and stop myself from ever killing them, even the one I killed on accident and in self-defense."
Sweetie Belle cocked her head. "On accident and in self-defense?"
"Yes, they were coming towards me to beat me up and I hit the leader on the head with a rock." Rarity moved over to her workbench and levitated the stone in question out of its spot. "This rock, as a matter of fact."
Sweetie Belle took the rock from Rarity and examined it for a few seconds before handing it back to her sister.
"Can I watch the next time you do it at least?"
"Absolutely not! I don't want you to be part of this." Rarity put a hoof on Sweetie Belle's shoulder. "Please trust me on this. I want you to promise big sister that you'll never hurt anypony. Take solace in the fact that you have good friends. I didn't have friends like you do now back when I was your age. I was too busy with..." She motioned around the room. "This."
Sweetie Belle nodded. She began walking back towards the stairs. "I understand, sis." She walked up a few more steps before she turned back to Rarity. "I don't hate you for this."
"That's more than I deserve, Sweetie Belle. What I've done merits death."
Sweetie Belle merely shrugged and walked back up the stairs.
Rarity moved over to her workbench and gently placed the rock back in its usual place. As she adjusted the rock, she took a good long look at her collection of knives and imagined how Sweetie Belle must have felt when she saw it. To think that an innocent filly like her had seen them and understood what Rarity used them for was disheartening. She sat down and ran her hoof over the handles of a few of them, remembering what she had done with them. To her surprise, she felt tears begin to well up in her eyes. She quickly slammed her workbench to hide her tools of death.
"What have I done to you, Sweetie Belle?" Rarity whispered. Finally her emotions overwhelmed her and she put her head in her forelegs and cried.