"Are you certain that this is wise, sister?" Luna asked quietly as they sat within Celestia's chambers. "With all that has happened, I fear that Twilight Sparkle may not be the most objective pony when it comes to Starlight Glimmer."
It had been three weeks since Celestia received an urgent letter from Rarity that she was desperately needed in Ponyville. When she arrived she found Twilight more furious than she'd ever seen, being held back only by Rainbow Dash and Applejack as she railed against a heavily injured Starlight Glimmer.
Binding Starlight so that she could not escape, she and Twilight's friends were able to calm her from her murderous rage and at last receive a clear explanation of what exactly had happened. What followed was a tale unlike any Celestia had ever heard. Starlight Glimmer's had come to rob Twilight of her friends by disrupting Rainbow Dash's Sonic Rainboom using a modified spell devised by Starswirl the Bearded. After being forced back and forth between that moment in time and the many dark futures that it's disruption created, Twilight was finally able to overcome her and return time to it's proper alignment.
But only at a terrible cost. In an attempt to aid Twilight in distracting Starlight long enough that the rainboom could be completed and time could be restored, Spike had thrown himself at Starlight, biting and clawing at any part of her that he could reach. The rainboom commenced shortly after and before they were returned to the present, Spike was flung from Starlight's neck, out of range of the spell's ability to drag him through before he plummeted to the ground.
Twilight remained distraught as she relayed her tale, alternating between sorrow and rage and demanding that she be allowed to avenge him. It was a request Celestia was unable to grant her, eventually soothing her with help from her equally distraught friends. "Starlight Glimmer will face justice for her crimes." That was her vow and she intended to keep it.
That led them here in Celestia's chambers and waiting for Twilight's arrival. "She insisted that she wished to be involved in the decision." Celestia replied. "I share your concerns, Luna. I would much rather that she stay in Ponyville and continue her recovery. But I am also inclined to include her, if only to hear a third perspective from a pony who has encountered the accused twice over and is the only victim we have of this latest crime of hers." She smiled gently. "I trust her, Luna. Twilight has been through an ordeal, it is true, but I am confident she will make it through this and that beneath her pain and loss, she is still the same pony I took on as my student so long ago."
"Mmm," Luna hummed quietly, her ear flicking up to catch a sound of approaching hoofsteps. "I pray you are correct."
The doors opened moments later and Twilight entered, thanking the guard who had opened the door for her before it was shut behind her. She looked like she had gotten some amount of sleep since they'd last seen each other, but it was clear that she'd lost some weight. Without waiting for a greeting, Celestia approached her and brought her into a gentle hug, wishing so very much that she could take back all of this darkness that had befallen her faithful student. "How are you, Twilight?" Celestia asked.
"Some moments are harder than others, Princess." Twilight admitted sadly, patting Celestia on the back before reluctantly releasing the hug. "My friends have been a big help, but I can tell they're grieving too. All of Ponyville seems to be in mourning now that word's starting to spread."
"You have my deepest condolences Twilight Sparkle." Luna said, approaching Twilight as well and sharing a small hug with her. "I know that you have not been sleeping often, but I hope you have been resting none the less."
Twilight smiled and returned the hug. "Yes Luna, I guess I should thank you for the pleasant dreams I've had these last few weeks."
"I only lament that I cannot do more to aid you."
"Shall I pour you some tea?" Celestia asked, approaching the table.
"No, thanks. I've not been hungry lately." She followed behind the sisters. "Honestly, I just want to get this over with."
"Of course." Celestia agreed, joining Twilight and her sister in sitting down before one of the three sets of papers. Picking them up with her magic, Celestia glanced through them with a sigh. "It is a long list of very serious charges."
"Twenty-nine counts of false imprisonment." Twilight muttered, not bothering to look through them. "Twenty-three counts of brainwashing, six counts of attempted brainwashing. Ninety-seven counts of assault. Cutie Mark removal is not a spell specified as illegal but it should be safe to assume that it can be filed under twenty-nine counts of Use of Forbidden Magic." Twilight looked down. "And finally one count of murder in the first degree."
Celestia and Luna shared a look, seeing that Twilight had been thinking a great deal about Starlight Glimmer these last few weeks. "Twilight," Celestia began, about to suggest that maybe she shouldn't force herself to do this so soon after what had happened.
"I'm fine." Twilight said sharply, taking a deep breath to compose herself before continuing. "Capital punishment is the only thing that fits the number and magnitude of her crimes. That leaves us five options. Banishment, a lifetime of incarceration without the possibility of parole, petrification, and execution."
"There has not been an execution in Equestria in over a thousand years." Celestia noted.
"And I see no reason to break that streak."
The sisters looked at Twilight, surprise evident on theirs faces. "I am surprised, Twilight Sparkle." Luna admitted. "I must admit that I expected you above anypony else to be pushing for her death."
"I'm not a murderer." Twilight muttered coldly. Again, an oppressive silence fell over the table for a time. Celestia regarded her sadly. She did not like to see such anger and coldness out of her student. She could see the pain of her loss was still fresh in her mind.
"Regardless," Twilight continued, breaking the silence before Celestia or Luna could try to dissuade her. "Execution is not the best solution. Banishment leaves her the chance, however remote, to one day return to cause more harm. She is a very clever and very powerful unicorn so there are few prisons within Equestria that could hold her. Even then, we would need a very powerful magic sealing spells and near twenty four hour surveillance, both of which will take time to set up while she is already formulating some means to escape from the Canterlot dungeon." Twilight stopped her analysis as her eye fell on Celestia. "And given Discord's account of what petrification is like for the victim, I doubt it's a punishment you're eager to perform Princess." Celestia sighed, a silent admission of that fact. All these years she thought it would simply freeze somepony in time until they were released, but to know they were still conscious though the entirety still pained her.
"Hold on, Twilight Sparkle." Luna interrupted. "You said there were five options, but I count only six that you have listed."
Twilight allowed herself a faint smile. "That's because the last option is...unorthodox."
"How so?" Celestia asked.
"It involves a spell I've been working on with some help from the College of the Elks. It's a combination of two spells they use for psychiatry and mental health. The first involves using magic to alter bad memories to deal with post traumatic stress and similar disorders. The second is riskier, but involves changing a patient's personality to help them overcome various behavioral disorders. Depression, phobias, things like that. By combining both spells, I've refined the result into something I call 'The Death of Personality'."
"Tis a morbid name." Luna commented.
"I know. But I think it suits it rather well." Twilight continued. "Once cast, the spell will completely erase her memories and personality. Once that is done, the caster will use the original component spells to implant a new personality and memories. In this case, I'm thinking of implanting a love of helping others, and a upbringing emphasizing a dedication to community service. Then we send her off somewhere remote, maybe with an undercover guard who's looking for a nice quiet retirement and won't mind keeping an eye on her for anything unusual."
Another silence followed as Twilight finished her proposal. Celstia's face had become unreadable, a sign that she was deep in thought on the matter. Luna, on the other hoof, made her opinion much more easily known. "Absolutely not!" She declared, appalled by the suggestion. "To tamper with another pony's mind like that? It is a power that no pony in the land should possess!"
"She will still live." Twilight replied calmly. "There will be no risk of her returning to cause more trouble, as there would be with life imprisonment or banishment. Her talents will not be wasted as they would be with an actual execution or petrification and will be ut to use in service to the ponies she very nearly destroyed."
"'Death of Personality'." Luna snapped. "That is the title you have given this sentencing, is it not? Do not play word games with us, Twilight Sparkle. By erasing her memories and personality, you are destroying that which makes her who she is. You are preserving her physical life at the expense of that which makes her unique."
"That is the intent of the punishment." Twilight retorted, a coldness appearing in her tone. "With one spell, all that gives her the ability to conceive of the terrible things she has done will be wiped away. No long term incarceration, no counseling to make her see the error of her ways, an all new pony who is a happy and productive member of society."
"And what of her soul?" Luna demanded.
"What of her soul?" Twilight snapped back.
"By erasing her personality and memories, do you not destroy her soul?" Luna asked. "And if not, does that then mean that her soul will remain trapped within a mind and body that is no longer hers?"
Twilight barely hid her smile. "I fail to see how that's relevant. If we did execute her, we both know that she's doomed to Tartarus for what she's done. I'd argue that letting her spend the rest of her life here, as a happy and peaceful pony is a fine reprieve from whatever is waiting for her when she dies."
"What was the purpose of creating this spell, Twilight?"
Twilight turned to look at Celestia. "Hmm?"
Celestia was watching her, her eyes peering deep into Twilight as she explained. "Tell me truthfully; You have seemingly gone to a great deal of trouble to create this spell, which you had no reason to believe you would require until a few weeks ago. Is this a matter of justice for you, or of revenge? "
Twilight said nothing, staring back into Celestia's eyes with a pensive expression. Luna looked back upon her as well, seeing the gears behind her head turning. Eventually, Twilight turned away, walking across the room to stare out the window. "Twilight Sparkle?" Luna prompted, her concern growing as she broke the silence.
"Revenge." Twilight admitted quietly, the smallest of smiles crossing her face as she caught sight of her reflection. "It's about revenge."
Celestia sighed, having been afraid of this answer. "Twilight, you know that this cannot be-"
"You weren't there." Twilight interrupted, staring Celestia down. "You didn't see it. She'd have ruined everything. Everything we've built, everything we've accomplished. Equestria would become an absolute wasteland where there was no life or any sign of civilization. Discord or Tirek running rampant through the land. Chrysalis having free rein of Canterlot and about to crush the last of the resistance. King Sombra leading the Crystal Empire in a war against Equestria that had no end in sight." She looked back at Luna and the princess felt her body tense as she knew what came next. "Nightmare Moon, living as an absolute ruler with her sister imprisoned in the moon forever." Twilight looked down. "My friends, miserable and unable to recognize me or each other. All because of her and her petty, poorly conceived plot of revenge."
For a moment, anger flashed on Twilight's face. "Yes. I admit that this is absolutely about revenge. I want to make her pay for what she did. I want to take away everything from her the way she tried to take everything away from me. I want to watch as the spell takes it's course and she loses every memory she's ever had, and her personality fades away into nothing until 'Starlight Glimmer' disappears forever, never to darken a doorway again."
Her smile returned, twisted by her anger. "But I'm going to be different. I'm going to be better than she ever was. Because unlike her, when I'm done, she won't be left in despair without any friends in a broken world that should not be, or trapped in a loop, fighting a battle forever and ever for no higher cause than her own spite. I'm not going to murder her friend." She returned to the table, her smile growing on her face as she let herself imagine it. "I'm going to build her back up into something wonderful. A polite, friendly pony who's greatest joy will be to help others and perform community service for Equestria. She'll get to go on and live happily and at peace, making friends; never knowing what she'd done or the harm she caused." She closed her eyes quietly relishing in the imagery. "It's a perfect solution, don't you think? Everypony wins and everypony lives."
"No." Luna countered, frowning deeply. "Tis but a more horrific form of execution. Wiping away the mind and putting something false within it? At least Nightmare Moon only usurped my mind. You wish to erase another's will completely. I can think of few fates worse than that."
"It's better than she deserves." Twilight replied simply.
Luna glared at Twilight openly now, visibly repulsed by the casual nature by which Twilight was able to dismiss the moral concerns she had about this plan. Twilight, however, tried to keep up a friendly smile, seeing this as a debate on the nature of what she was proposing, but unwilling to back down from this punishment that, to her mind, would satisfy everypony. "I can see I'm not going to convince you, Luna." She said. "Perhaps we can put it to a vote?"
Celestia regarded Twilight. "You would accept such a thing? Even if it denied you your revenge?"
Twilight again fell silent for a long time, thinking about her answer and what it meant. "I think it's near enough to the truth to say that I wouldn't like it." She replied softly. "In fact, even if I got my way and erased her by my own horn, I doubt it would make me feel better. But I really do believe this is the best choice for everypony. Starlight gets a second chance that she would not have otherwise, and I can rest assured that the pony who... who killed Spike is gone forever." She looked between the sisters before settling back on Celestia. "You promised me that she would face justice, Princess, and I don't think either of us are going to budge. So it comes down to your decision. You've been at this long than I've been alive, so for better or worse, I'll go along with whatever you decide."
Celestia closed her eyes, thinking long and hard on all that had been said. Twilight's solution was indeed elegant in design and extremely thorough. A single casting of the spell, and a pony who was once unrepentantly evil and malicious became a model citizen. They would even enjoy their new life with no memory of who they used to be. They could bring all those who refused to live in harmony with others into line. But Twilight's motives were those of a darkness she did not like to see in her student and Luna's points were not unfounded. There were far reaching moral and ethical implications to this decision, that could change the way crime and punishment was looked at for generations within Equestria and even the world. Did they have that right? Did anypony have that right?
She took a deep breath and opened her eyes looking between both her student and her sister before finally giving her answer.