Rarity screamed once more, the remaining working part of her mind wondering if this was really how it was all going to end. That part of her couldn't believe that Twilight was really going to kill her in an ironic vigilante sort of way.
She continued to try to struggle out of the straps as Twilight came closer with the knife. When she got close enough, she looked Rarity directly in the eye. "Goodbye, murderer."
Rarity squealed in terror and shut her eyes, hoping that Twilight would at least make it quick.
"NO!" squeaked a voice from behind them. Twilight turned around and Rarity opened her eyes in time to see Sweetie Belle run towards Rarity, pushing over the tray so she could grab one of the smaller knives. She placed herself between Twilight and Rarity, pointing the knife towards Twilight. It was a pointless effort because if Twilight truly did want to kill Rarity, she would just use her magic to shove her aside. As it was though, Twilight looked like she was about to cry. "NO! I won't let you hurt my sister!" Sweetie Belle took a step forward and jabbed the knife towards Twilight. "She may be a killer, but she is still my sister and the only one that I have. She'd do anything to protect me, and she'd do anything to protect you! You don't have the right to just butcher her like an animal!"
Twilight's lower jaw quivered, and a pair of tears streaked down her face. "I-I wasn't gonna kill her," she said taking a step towards Sweetie Belle. Sweetie Belle flinched back for a moment, but recovered and lunged forward with the knife. Twilight managed to dodge back fast enough that she was only received a slight cut on her knee. Twilight gasped in pain and dropped her knife on the ground. "No, I wasn't going to hurt her at all!"
"Then why is she trapped down and why were you standing over her holding a knife?!" Sweetie Belle snapped.
"I just wanted her to know how it feels for the ponies she kills!" said Twilight. "I wanted her to experience what it is like being strapped down to her table, knowing that these are your last moments and that they'll be spent in excruciating agony. I just wanted her to know what she's done!" Sweetie Belle paused at this and looked less sure of herself. She slowly lowered her knife and looked back at her sister. Twilight used her magic to put the tray upright and she put her knife back on it. "I wasn't gonna hurt her."
Twilight's horn fired up, and Rarity felt the straps holding her down loosen. She was surrounded by Twilight's magical glow, and she felt herself being carried back up the stairs by Twilight. When they reached the top, Twilight placed Rarity back into her wheelchair and, once Sweetie Belle had left the basement, she shut the door behind her.
Twilight wheeled Rarity into the middle of the room before turning back to Sweetie Belle. "I'm not gonna hurt your sister, Sweetie Belle. I Pinkie Promise that I will not hurt her. However, I'm going to have to take her back to my house with me because there are just certain things that I have to know."
Sweetie Belle's bottom lip began to quiver and she broke down crying. "Don't hurt her, please don't ever hurt her."
Twilight sighed and wheeled Rarity out the door leaving a crying Sweetie Belle alone in the house.
The journey back to Twilight's house was a silent one. Rarity spent the ride over calming her body down, taking deep breaths and trying to clear her head. Twilight wasn't going to kill her; she had never intended to hurt her. She wasn't going to die.
When they reached Twilight's house, Spike was already fast asleep in his basket, so both of them knew that they wouldn't be disturbed with whatever Twilight was planning. Twilight used her magic to lift Rarity and her wheelchair into the air, and she moved Rarity into her basement where she had the memory machine waiting.
"Twilight, what's going on?" asked Rarity, hoping that Twilight wouldn't force herself to watch all of Rarity's kills.
Twilight was silent for a moment while she placed the headband on Rarity's head. "Is there a specific memory or time period that made you be this way?"
Rarity nodded. "It was a few months into my first year of school. I had never had any desire to hurt anypony for any reason whatsoever before that. But one day I was cornered by three bullies and... well, after that day I had three kills to my name."
Twilight asked Rarity which date she was referring to and Rarity told her, prompting Twilight to type it into the memory machine. Rarity felt a tingle as the memory machine fired up, and the memory began playing. Rarity directed Twilight to specific moments, and Twilight made the necessary adjustments to play those times.
Rarity and Twilight watched in silence as Rarity's second worst memory began to play on the view screen. There were Dug, Kicker and Annie, once again tormenting her in the schoolyard. There was filly Cheerilee standing up for her. Now Rarity was in her creek, trying to stop the bullies from tainting her land. There was the rock that would be her first murder weapon; there she was smashing Dug's head in, killing Kicker, burying Annie alive.
It was after that last one that Twilight shut the machine off. She turned back to Rarity and she saw that Twilight was crying. "I had no idea."
"I know that doesn't justify what I am," said Rarity.
"You mean who you are?" said Twilight.
"No, what I am. I'm a monster Twilight. I've known that I was a monster and would forever be one ever since I was scooping dirt back into a hole containing a dying filly." Rarity sighed and flattened her ears. "I don't deserve to live and I know that you have to turn me in. I appreciate you erasing Sweetie Belle's memory of committing a murder herself, but as for me, do what you must."
Twilight continued looking at Rarity. Rarity knew that the gears in Twilight's head were turning, trying to decide exactly what to do.
"I don't think that you are a monster, Rarity. Your urges to murder are the unfortunate product of a terrible thing that happened to you." Twilight gave Rarity a small, sad smile. "If I know anything about the Elements of Harmony, it’s that they don't choose a wielder lightly. They know what they are doing. They see something inside of you, some good trait that makes the Element of Generosity drawn to you. The Elements of Harmony would never choose a true monster to wield them."
"But they did!" said Rarity. "Do you have any idea of what I have done? I am an evil being beyond saving! Princess Celestia would strike me down where I stood if she ever found out!" Rarity sighed and looked down. "And I know that you have to tell her. In all honesty Twilight, I won't stop killing until I am ended myself. I do not kill the innocent anymore, but there is nothing that I can do about what I am. You should go tell her now, Twilight. My family and our friends will suffer with the knowledge that they accepted a psychopath into their lives, but time will heal those wounds to the point that they can live life again."
Twilight wheeled the machine back into its closet and sighed. "You only kill to protect?"
"Ever since I met you girls, yes. Before that I killed for fun or for petty reasons that wouldn't have mattered if I had just left them alone. I never want you girls to experience what I had to." Rarity scoffed. "I mean, look at how I turned out."
Twilight nodded. "I don't know if I can let you keep going. I don't want anypony to die because you feel that it is your duty to protect us from the bad things of this world. I don't want anypony to die. I didn't wish death upon Gilda or Trixie for the way that they acted, but they got it anyway at your hooves."
"So are you going to tell Princess Celestia?" asked Rarity.
"No, but I have to tell somepony about this," said Twilight and oddly enough, a small smile stretched across her face. "And I think I know just the pony to tell. Wait right here." Twilight left the basement and was gone for about twenty minutes. Each of those minutes seemed to be an eternity for Rarity but eventually Twilight did come back down. "Okay, she should be here very soon."
"Who did you contact?" asked Rarity.
"You'll know when she comes," said Twilight. Rarity ground her teeth together slightly. Twilight was annoying when she was being ambiguous like that.
After about twenty more minutes, that Twilight spent giving Rarity a tutorial of the memory machine, they heard the door to Twilight's house open. They heard hoofsteps growing steadily louder as this mystery pony approached the basement door. Rarity turned her wheelchair around just in time to see the last pony she expected to see walk through the basement door.