//------------------------------//
// How It Should Have Ended, pt. 1 
// Story: Equestria Girls: How It Should Have Ended 
// by PrometheusX 
//------------------------------//

"The crown may be upon your head, Sunset Shimmer, but you cannot wield it, because you do not possess the most powerful magic of all: the magic of friendship!"

Sunset Shimmer couldn't believe what was happening right in front of her. She finally had everything she needed to conquer Equestria and take what should have been hers all along. She had magic, she had an army, and she had the will to use both as she saw fit.

And yet somehow, it was all falling apart before her very eyes. All because of five little humans, a dog, and a princess who didn't belong in this world!

'This shouldn't be possible! The crown was supposed to obey me! Why is it giving her power?!'

Yet she couldn't deny the stream of pink magic leeching from the crown upon her head and towards the mare turned human known as Twilight Sparkle. She could feel the power leaving it and being absorbed by her, the empowering effects it was giving to her and her little 'friends'.

Then again, why shouldn't it? After all, Twilight Sparkle was the true bearer of the Element of Magic, the greatest of all of Equestria's virtues. She might have been able to pervert it to her own ends, but she couldn't make it hers alone. It would always obey the call of its real master.

A real princess of Equestria, who even now with her friends was about to pass judgement on her for her crimes.

Sunset's shock turned to anger at that realization. Of course it would be that way. That's all she was in the end, wasn't she? A fake, a pretender to the throne? She had left Celestia when she refused to make her a princess, contented herself with ruling a high school of little idiots in a world without magic, and very soon she wouldn't even have that. She would be a nobody, a pathetic little footnote on history.

'No! It can't end like this! I won't let it end like this!'

With a snarl of hatred she reached up with her clawed hand and grasped the Element of Magic on her head. She took dark pleasure in noticing Twilight's confident smile turn to uncertainty and then shock as she wrenched the pathetic piece of jewelry off her head and hurled it at her 'successor'. The suddenness of her action was so unexpected that for a moment her enemies' focus shattered as Twilight reached out to grab the crown.

All the time Sunset needed to cast a new spell. A dark bubble of cyan surrounded the pink glow of the six, trapping them in place. Dark lightning then flashed out and struck at them from the inside, only to fade as it struck the pink glow, shielding them from harm.

"Little fool! You dare pass judgement on me?" Sunset snarled, "Me?! You dare to think you're a match for me just because you have wings and a crown? Because you have a few superficial traits that in no way determine your power or your cunning?! 'Magic of friendship'? Let's see how high and mighty you sound when that pretty glow of yours fails!"

She couldn't hear Twilight Sparkle's response from within the bubble, though she doubted it was anything resembling begging for mercy. The fact that Rainbow Dash was throwing her a very insulting hand sign was enough to prove that. Growling, she decided to see how that glow would protect them from a crushing effects of a shrinking sphere.

At least until she felt something bite her ankle.

"Owch!" she yelped as she looked down, noticing that little purple dog that came with Twilight through the portal, the very same one she tried to blackmail Twilight into giving her the crown in the first place, hanging on her leg, growling angrily.

"'Et th'm go!"

Sunset narrowed her eyes right before wildly swinging her foot, forcing him off to impact on the ground with a yelp. "Little pest! You're next!"

A cracking noise was all the warning Sunset got before she looked back and saw her bubble shatter like glass, six very angry-looking girls staring at her with white lightning crackling around their bodies. The intensity of their glares was so strong she actually moved back in shock before recovering herself.

"It's over, Sunset Shimmer!" Twilight proclaimed as they formed a heart shape and the lightning intensified, "It's time for you to pay for your crimes!"

But even as they did so, Sunset's eyes, quite on accident, landed on the still-waiting portal, her method of returning to Equestria as a conqueror. Suddenly, an idea struck her, one so simple that she actually chided herself for not using it earlier. It was essentially saying she had lost, but at least she wouldn't go down alone.

"You're right, Twilight Sparkle. But not just yet!"

She snapped her fingers, her two demonized minions Snips and Snails appearing right in front of her. They looked around uselessly for a moment, dazed by the sudden teleportation, before she grabbed them and hurled them both at the six girls. Right on cue, Twilight and company fired a massive rainbow-colored beam aimed right at her, only to strike the two bumbling fools instead, surrounding them in a rainbow twister of sorts.

"Au revoir, Twilight Sparkle!" Sunset Shimmer cackled as she spread her bat wings and rushed straight the surprised six, aiming straight for the portal. As she touched the surface, she felt it shimmer and bend around her form as she passed through, already feeling the effects of her transformation into a pony upon her new form.

Before she passed all the way through though, she remembered something one last thing and jabbed a finger back towards the school entrance, firing a small blast of pure energy at that goody two-shoes Flash Sentry and sending him crashing flat on his ass. Petty of her, but he did get in the way of her discrediting of Twilight and she seemed to like him, so an attack on him was an attack on the princess and that suited her just fine, even if they had dated for a time. The fact he was still a zombie was the only thing that sullied it.

Speaking of which, her last sight before entering the portal completely was of Twilight and company unleashing another rainbow wave that struck her teenage zombie army, turning them back to normal. And with it, all of her planning and work was undone. Anger again rose, but she quieted it upon reminding herself of one important fact.

Twilight Sparkle might have stopped her plans here, but she would have to come through the portal for her if she wanted to finish it. Sunset understood that very well. That little princess could never leave Equestria undefended.

It was sad in a way though. At least if she stayed in the human world she wouldn't have to see the things she already planned on doing to her friends and family. After all, they were expecting their princess to emerge victorious, not a vengeful demon.

'I can't wait to see the look on your face, Celestia!'

Still, Sunset was under no illusions of what she was about to do. Even with her thoughts clouded by madness she knew what the ultimate result of facing down three alicorn princesses and the other five Element bearers by herself without an army to back her would result in. But for her, that didn't matter anymore. If she could bring down even a few of them with her, it would be worth whatever fate Celestia chose for her. The look on Twilight's face when she came through the mirror would be more than worth the sacrifice.

'You took everything from me, Twilight Sparkle. It's only right that I take some things from you too.'

As she felt her form shift into a more equinoid one, she suddenly hit upon another idea. Not knowing if it would work or not, she concentrated and casted, 'nodding' with sick pleasure as she felt the spell take effect even despite the changing properties of the mirror. With luck, it would buy her a few more moments of time, and it would just be icing on the cake for her plan.

'No, this isn't right. This isn't me...'

She 'blinked' as that strange thought crossed her mind, then dismissed it. It was nothing, just a figment of her imagination. Besides, who cared if what she was doing wasn't right? She thought it was, and thus it was.

She perked up as she saw a light at the end of the darkness of the mirror's passage. It was time.





Celestia sighed quietly to herself as she, Luna, Cadance and the rest of Twilight's friends waited in front of the Crystal Mirror for the purple alicorn's return. For nearly two days they had waited for some sign of Twilight's return with the Element of Magic, and for two days she had wondered to herself if whether or not it had been a wise choice to only allow her student to travel through the mirror. She hadn't lied when she said that having all of the Mane Six go through the mirror could very well disrupt the balance of the alternate world, but she was also forced to admit to herself that there was a very high chance that they would have long ago returned with the crown if she had allowed it and thereby minimize any risk to the alternate world.

Again, she wondered if it had been the fact that the culprit in question had been Sunset Shimmer that had spurred her ultimate decision. Was it not right and poetic that Twilight Sparkle, the student who succeeded where Sunset failed, be sent to stop her alone? But if so, Celestia wondered, was she risking the fate of two worlds and the safety of her pupil all in the name of trying to teach a lesson to a student who had clearly stopped wanting to learn?

'At least she has Spike,' she tried to assure herself. 'More than any other, he'll do everything in his power to help her succeed.'

It was small comfort, but at least it availed some of the worry and guilt within her.

Suddenly, the portal rippled. Everypony's eyes were immediately drawn to the mirror as it flashed with a burst of light. For a moment, Celestia felt her worry and fear soar, right before it faded into relief at the sight of Twilight emerging from the portal, strangely enough standing on her hind legs as if trying to balance on them before falling to her hooves.

"Twilight!" Fluttershy cried out gratefully.

"Ah, you're back!" Rainbow Dash added as the rest of her friends crowded around her in happiness. Celestia moved to join them, but stopped when she noticed something...odd. The way that Twilight looked at them, while on the surface seemed happy, almost seemed...forced?

Rarity noticed something else, her face scrunching up in confusion. "Dear, where's your crown? Certainly you got it back from that dreadful Sunset Shimmer, right?"

Twilight blinked, then bowed her head. "I-I'm sorry, everypony, b-but I..."

"You couldn't get your crown back?" Cadance asked, her voice full of concern. "What happened?"

"Sunset Shimmer...she did something to the Element...made it...darker somehow..."

Was it just the light, or did Twilight's eyes just flash with hatred at Cadance's voice? Celestia's confusion grew, and with it warning bells started blaring in her mind.

But before she could open her mouth, Applejack looked behind Twilight at the mirror. "Hey, where's Spike? Shouldn't he'd be with ya?"

Twilight looked behind herself at the mirror. "Oh, he'll be along soon enough..."

Maybe it was the way Twilight said the words with a strange sort of relish or perhaps it was the way her body suddenly tensed up. Or perhaps it was how Pinkie Pie seemed to suddenly undergo a seizure, shaking and quaking rapidly in place. Immediately, Celestia realized that this wasn't the Twilight they knew. And there was only one other pony it could be-

"Wait a minute, you're not Twilight!" Pinkie Pie started to shout as she pointed at Twilight dramatically. "You're a-"

"Get back!" Celestia shouted as she tried to cast a spell, her horn lighting up gold.

Unfortunately, the imposter was faster.

A wall of force erupted from around the false Twilight, sending everypony, even the princesses, flying back into the walls. Upon impact, said force pinned them all to the walls with invisible bonds, the intensity of which surprised even Celestia. Even then, she could feel another spell settling over the room, almost like a bubble of sorts.

'What power,' the white alicorn thought to herself. 'How could she have gotten so much so-'

"Surprised, everypony?" 'Twilight' said with a smile that looked more deserving on the face of King Sombra. "Unfortunately, I don't have to play around. Luckily, that barrier will deal with any interlopers and keep any of you from leaving."

Her form shimmered like mist before the illusion faded away, revealing another alicorn underneath. Much larger than Twilight, she neared Celestia herself in terms of size and even bore a similar cutie mark of the sun, though that was where any similarities ended. A breastplate of black and gold surrounded her chest and pointed red hoofguards covered her hooves. Her coat was the color of dried blood, leathery bat wings proudly unfurled for all to see. Her mane and tail seemed to move as if on fire, and pointed ears flickered every which way. She smiled again, and quickly showed sharpened fangs fit for a dragon within.

But it was the eyes that held the attention. Cyan with black sclera, they gazed upon everypony with hatred so intense that Celestia almost expected them all to burst into flames at the fury. They were the eyes of madness, of anger and resentment finally allowed to bubble freely to the surface.

For a moment, it was as if Nightmare Moon herself had been reborn, but with sun, not the moon as the symbol of her power. And just as back then, Celestia felt her heart rip in two at seeing somepony she loved fall so far.

"Hello, Princess Celestia," Sunset Shimmer said proudly at the sight of her teacher's grief-stricken face, her horn crackling with cyan and black energy. "I'm finally home."





'This can't be happening,' Twilight thought desperately to herself as she rushed towards the portal, any joy at having gotten her Element back or saving the school now secondary to the growing horror of thinking about what the demonized Sunset Shimmer would do now free in Equestria. Back there, not only would she have the stolen power she gained from the crown but also her own magical abilities restored, the combined might of which could be devastating to whoever was still waiting on the other side. 'I've got to stop her!'

Only to find herself suddenly being jerked back as both Applejack and Rainbow Dash grabbed hold of her.

"Twilight, calm down!" Rarity shouted. "If you go charging in there without a clear head, who knows what will happen?"

"I have to get back!" Twilight told her newfound friends, struggling to break free. "I've got to stop Sunset Shimmer from doing anything else!"

"Then let us come with you!" Rainbow Dash grunted. "We stopped her army here, we can stop her over there."

"I can't!" she shouted, but she did calm down slightly, her struggles slowing. "That's why I didn't bring my friends from Equestria over here. Having all of you together could cause something catastrophic to happen!"

"Oh! Oh! You mean like a 'never the selves shall meet' kind of thing where the world goes kaboom?" Pinkie Pie asked as she scratched her chin, deep in thought. "But if that was the case, even shouldn't the world have collapsed in on itself the moment Sunset Shimmer came across the portal if there's a human version of her here? As a matter of fact, why would getting near each other even do that? Wouldn't the fact that two identical versions of yourself in the same reality do that regardless of proximity..."

"That may be," Applejack admitted, ignoring her friend's rambling, "but if y'all just charge in there without a plan, you're not gonna get much of anything of use done. What you need to do is calm down and think logically for a sec'."

Twilight finally stopped struggling, the realization of what Applejack was saying kicking in. This was not the time to be reckless, as to do so could mean even worse things happening. Applejack and Rainbow Dash finally let go of Twilight when they felt her cease, and the pony-turned-human took a second rub her arms where they had gripped her before nodding her head.

"Thanks..."

"No problem," Rainbow Dash smirked, then looked at the portal. "So, what's the plan for the devil reject?"

A few ideas were already spinning in Twilight's head, words and actions of Sunset coming back to her, along with Celestia's words and her own conclusions. "The plan," she began, "involves me and Spike going back to Equestria while you girls stay here."

"But-" Fluttershy began, but Twilight cut her off.

"No buts. I have an idea of how to finish this, but I have to do it alone." Noticing their worried looks, she flashed them all a smile. "Hey, don't worry. I'm coming back. After all, I still have a dance to finish."

Spike rushed over to her, tail wagging worriedly. "Well, we better hurry! We have less than an hour before the portal shuts, remember?"

Twilight nodded, then noticed the crowd approaching from within the school. "Just keep them busy for a little bit...and tell them to clear a path directly in front of the portal. Can you guys do that?"

The five girls looked at each other and then nodded. "Count on it," they said as one.

Twilight smiled once more and raced towards the portal, Spike at her heels.

"You know, if you want to-" she began, but Spike cut her off.

"They can handle things over here. I'm not gonna let you fight some raging she-demon without a little backup, okay?"

Twilight sighed gratefully. "Have I ever told you that you're the best assistant a librarian could ever ask for?"

Spike grinned. "You could stand to mention it a little more."

With that, they jumped through the portal once more.





Twilight wasn't certain of exactly what to expect once she and Spike were through the portal. After an intense feeling of vertigo, she found herself trying to balance on her hind legs back in the Crystal Empire, attempting to shake off the effects of her trip. Spike was no better, having fallen on his stomach and trying to make his limbs move properly. With a grunt she fell back on her hooves, shaking her head to clear out the confusion before finally getting a clear view of the room.

It was chaos, for lack of a better term. Scorch marks and cracks covered the crystal walls and furniture had been upturned if not utterly destroyed. There was smoke even rising from several craters, proof that magic had been used very recently.

"Twilight, look out!" came Spike's panicked shout.

And one such magic blast was currently heading her way.

Twilight acted on instinct, grabbing Spike, who was still suffering from the portal's effects, and teleporting out of the way. The blast struck the ground right in front of the mirror and sent pieces flying into the air, none of which managed to hit them as they reappeared some distance to the left. Twilight's head snapped upward to where the blast came from, only to stare uncomprehending for a few seconds.

Above her was Princess Luna, eyes glowing white with power as her horn crackled dark blue, a blade of made of what looked like dark lightning floating next to her...and she was currently fighting Cadance.

But it was not Cadance as Twilight knew her. Her eyes were green, and Twilight immediately remembered the spell Sunset had used to turn the school into zombies. But the transformation was even more pronounced here, as not only was Cadence's eyes green, but her body had seemingly undergone something similar to Snips and Snails, scale-like growths covering her form along with bat wings and sharpened teeth. She too wielded a sword, a blue magic rapier, and was swinging it rapidly against Luna to keep her on the defensive, though she couldn't break through the older alicorn's guard.

"Just give up, Auntie Luna!" she shouted angrily as her next strike was blocked. "Lady Sunset will destroy you the moment she's finished with Celestia!"

"My dear niece, I may have spent one thousand years on the moon, but do not assume for a moment that I can't defeat an upstart like her. My sister may not have the heart to finish her, but trust me when I say that I have no such reservations!"

Cadance moved back and fired a blue blast from her horn. Luna swung her blade and deflected it, before firing a much larger blast from her own horn. The demon attempted to erect a shield to defend herself, and for a moment it looked like it would hold before Luna's assault.

Right before a pink blast struck her from behind, shattering her concentration and with it the shield. Luna's attack smashed into Cadance and sent her flying into the wall behind her with enough force to leave a sizable imprint, right before she peeled off and crashed to the ground in an ignoble slump.

Twilight breathed a sigh of relief as her horn faded, grateful for the fact that the two alicorns hadn't realized she was there, so intent they were on trying to overpower the other. She quickly raced over to Luna, who had dispelled her blade and landed tiredly on the floor.

"Princess Luna! Are you alright?"

"I...I am quite fine, Twilight Sparkle..." the dark alicorn said in between gasps as she looked over at her savior, nodding with pleasure as she saw both Spike to the side and the Element of Magic upon the purple pony's head. "It would appear as if...you have succeeded in your goal."

Twilight's face hardened. "Not quite. Where's Sunset Shimmer? And where are my friends?"

"Sunset Shimmer...disguised herself as you...caught us all off-guard with her power. I managed to break free first...but she managed to use that strange manipulation magic on Cadance before I could do anything...and then she and my sister vanished for a 'private matter'..."

Luna took a moment to catch her breath. Up close, Twilight could see that the dark pony hadn't come out of her battle unscathed. Her regalia was cracked, dinged and scorched by both physical and magical forces, her coat covered with soot, and Twilight was certain there were claw marks on her hind legs and neck. Even one her eyes seemed to be swollen shut as if something hard had struck it.

"The last...was a gift from your friend Applejack...I had forgotten how hard an Earth pony can buck..."

Spike looked flabbergasted. "Applejack did that? But why would she-" he trailed off when he realized exactly why she would do something like that.

'Oh no,' Twilight thought desperately, thinking the same thing. 'Please don't let it be so!'

Luna simply gestured over to the far end of the room, a part strangely untouched by damage done elsewhere. The truth became apparent when Twilight realized it was blocked off by a force field whose color very much matched that of the mare before her. But more than that, Twilight could see what lied beyond the shield, and the sight chilled her blood.

Five ponies that Twilight recognized as her friends were all there, seemingly unconscious from the forces that had been unleashed within the chamber. However, it was the fact that all of them had the same scaly growths and bat wings as Cadence that sealed the deal for her.

"It would appear...that we all underestimated...just how far Sunset Shimmer would go in the name of her vengeance..." Luna said slowly. "Against the combined might of Cadance and your friends...further amplified by her foul magic and myself forced to hold back...it proved to be much more difficult than I imagined."

"Are they-" Spike began, but Luna raised her hoof.

"They are alive...though I daresay Rainbow Dash will be suffering from an amazing headache for the next few days. I have not had to use my 'Diamond Pony' trick since the day I faced down an dragon with a gem-encrusted head...and it still went down faster than she did."

Twilight sighed in relief at the news. "Can you help them?"

Luna smiled. "Twilight, I am the Princess of the Night. Dream magic is my domain, and it in and of itself is but a type of mind manipulation magic, which is what has been used here. The spell Sunset cast to change and turn them against us is well within my ability to undo. You have my word."

A rumble suddenly shook the palace, causing the three to look around as pieces of crystal fell from the ceiling. Now, Twilight could clearly see a hole clean through the ceiling and on up to the nighttime sky outside the palace itself. She was also certain she caught glimpses of both gold and cyan light blazing through said sky.

"What was that?!" Spike yelped.

Luna's face was grim. "That would be my sister and her wayward pupil. It would appear they are still quite busy."

Twilight's face turned serious as she remembered what still needed to be done. Turning to Luna, she stated her intentions plainly. "I have to go."

To her credit, the dark alicorn did not at all seem surprised at her words. "I would expect nothing less. Be on your guard though, Twilight. Sunset Shimmer may not be as powerful as other foes you've faced even with her transformation, but she is far more dangerous for the simple fact that she wants revenge on you personally for everything you've done."

Twilight nodded, deciding not to add that was actually a crucial part of her plan, even more so now that her friends on this side were out of commission.

"Spike, stay here and help Princess Luna in any way you can," she ordered as she spread her wings out in preparation for what she was going to do. "This is something I have to do alone."

With that, she cast her teleportation spell, leaving the dragon and the battered princess to save the brainwashed ponies.





"HAHAHAHAHA! Are you having fun, Celestia?" Sunset Shimmer roared as she fired another beam of energy at her enemy. "Because I'm just getting started!"

Celestia dodged the beam, firing her own only to watch Sunset dodge herself. However, that gave her time for the real attack, teleporting herself right behind the demon-alicorn and swinging a blade of light. Sparks flew as Sunset managed to form a shield about her form before creating a black and green battleaxe to take Celestia's head, which the alicorn only dodged by dropping out of the sky before it could connect.

"You're delaying the inevitable, Princess! Just give up and I promise I'll end it quickly!"

Celestia was of the opinion that the Crystal ponies were truly heavy sleepers, as despite the fact Sunset's roars seemed to be magically enhanced to boom across the sky, not a single pony had seemingly exited their home to see what was happening. Then again, they were very high above ground, though she wondered exactly how long that would last.

'Either way, I can't let this go on any longer,' she thought to herself. 'Each second wasted is another second she might choose to do something we all will regret.'

Looking up at Sunset's charging form, Celestia stopped her descent and fired several more blasts, already determining they would prove useless. Sure enough, Sunset easily twisted and turned her body to avoid the beams, showing surprising ability for one who had only just recently gained the power of flight. The demon took aim and fired another massive dark bolt of magic, one that Celestia couldn't afford to dodge since the city was directly beneath her and thus innocents were at risk.

Instead, Celestia dispelled her sword and conjured a massive shield of light almost as brilliant as the sun itself about her body. The dark magic struck it dead on, but failed to crack the shield even as the princess observed Sunset strain to shatter it.

"You think that will stop me?!" the demon roared angrily. "Stop underestimating me!"

The beam altered, now taking the form of a massive claw of darkness that wrapped around the shield and squeezed. Celestia understood that what was happening was nothing but a visible representation of their two spells clashing, but it was impossible to imagine it as anything other than an actual hand trying to squeeze her shield apart. She could even feel her shield threatening to buckle under the pressure, once more reminding her of the power that her former student now commanded.

"Do you see now, Celestia?" Sunset mocked as she continued to exert her power. "Do you see the depths of your folly? You tried to keep me from my destiny, and now I've surpassed even you! You should have known better than to banish me!"

Celestia just sighed, her eyes closed. "Sunset, I've failed you."

"I realized that a long time ago," the demon replied as she increased the pressure, determined to crush the shield like an egg and hold her helpless teacher before her. "You always claimed you were just trying to 'teach me right', but the reality was you feared what I was becoming! Couldn't teach me this or that because I always reached too far, wanted to learn both sides of magic!"

"Especially the darker side."

"Of course. I didn't have a lot of time to test it out before you banished me, but it's more efficient and far stronger. I tried to tell you that." Sunset smiled a childlike smile of satisfaction. "But then again, even before then you were still holding me back, always keeping me at a distance."

"You're right, but not in the way you suspect." Celestia then opened her eyes. "I never meant to alienate you, Sunset."

"Lies! You hated me! When that pathetic pink princess Cadance came along she was always your favorite! Cadance did everything right! Cadance was so perfect! I showed the both of you, especially when I turned her into my willing slave!"

Celestia shook her head. "And that is where I failed you."

Her horn flared, a golden bow forming before her. Before Sunset could even react a single, gleaming shaft, a streak of blinding brilliance, shot forth from the weapon and unimpeded through the shield, since they shared both common origin and cause, and struck the menacing hand. Barely slowed, it continued through the palm and out the other end before either alicorn could even blink, passing right by the renegade face.

Immediately, the black claw released its grip and thrashed madly in the air above the princess, dissolving into nothingness. At the same time, Sunset threw her hoofs up to her horn and screamed in agony as if the arrow had pierced clean through it.

"W-What was that?!"

"That was one of my signature and most powerful spells," Celestia replied. "By drawing from the power of the sun itself, one can forge it into a bow and arrow that pierce all that stand before the caster. Those who mastered this spell were known as 'Sunlancers' in the old days, though 'Sun Archers' is more appropriate. Normally it requires the sun to be out to craft effectively, but I am the sun."

"J-Just one of the many magics you never b-believe I could use, huh?" Sunset panted. "Did you teach that one to Twilight as well?"

"No. As far as magic went, I taught you everything, Sunset Shimmer," Celestia remarked as she dropped her shield, flapping her wings to move closer to her former student. "I held back nothing. In time, all I knew would be yours to learn, light or dark. I hid nothing from you."

"I seem to remember something quite different from our last talk on that subject..."

Celestia's horn light up as gold rings snap into existence about Sunset's legs and horn, pining her in place and snapping her limbs out in a spread shape. "What I failed was to teach you compassion, to teach you empathy. I failed to teach the real power that friendship holds, to teach you that the world doesn't end at the tip of your own muzzle and only ambition tempered with restraint can hope to let you create your destiny. And now those very ambitions you held have let you twist yourself into a monster." 

"I'm not a monster! I'm enlightened!"

Celestia's eyes narrowed. Without a word she casted another spell, forming a mirror right in front of the renegade. Simple in form and decoration, it was quite large, enough to let a pony observe their whole reflected form. However, it seemed to shine with an inner light, casting a silver beacon that was nearly as blinding as the sun itself. However, none of that was as important to Celestia as to her reason for creating it: To make Sunset see.

See herself.

Sunset recoiled as if burned, only to pause in growing horror as her reflection mimicked her action. Celestia had no idea if Sunset reacted so because she had never bothered to fully observe her new form or if in her madness she saw herself as something more. Either way, the renegade stared as if Death itself was smiling at her, her breathing growing more and more rapid as her eyes roamed the image brought before her.

"No," she gasped. "That can't be-that can't be-" Her eyes turned to denial. "This is just another of your tricks!"

"A trick?" Celestia repeated. "I have played many tricks in my long life, Sunset Shimmer, but trust me when I say this is no act."

The demon struggled against her bonds, attempting to deny what stood plain before her. "Not possible...not possible!"

"This is your enlightenment?" Celestia demanded, her face grave and unforgiving. "This is your ambition? You've become no better than one of Equestria's greatest foes, Sunset! You've twisted yourself into a monster all in the name of power and desire! This is why I told you you weren't ready! This is what I saw if you continued down your path, and now you've finally fulfilled it."

Sunset roared, hate and denial evident in her voice. Her horn responded to her emotions, and for a brief moment Celestia's control was broken as the demon lashed out at the truth before her. The mirror exploded into shards, all of which missed both alicorns.

"This changes nothing!" she shrieked. "As an alicorn or a demon my plan will go on!"

Celestia sighed as she strengthened the bonds, unbelieving at the depths of her student's madness. "I truly have failed you, Sunset, but it's over now."

"What you failed to do was give me the respect I deserve!"

"I gave you all the respect you earned!" she finally snapped, her mask of emotion slipping away to reveal the grief-stricken pony beneath. "You never understood that, Sunset! Respect is earned! My love was what you never had to earn! Why did you always have them reversed, even now!?"

"Love?" Sunset spat. "What use do I have for love? Love is for weaklings who still rely on others. Love is for those who aren't strong enough to harden their hearts and take what they want. Love didn't save Cadance from my power, and it didn't help me when you banished me. You call me a monster? I don't care as long I have the power to do what I want!"

Celestia had to resist the tears that threatened to leave her eyes. She had hoped that on some level the student she had taken in as her own, had eventually come to see as her own daughter, was still alive within the monster before her. More and more that was becoming an unlikely possibility.

Still, she tried one more time. One more time before she would be forced to do what was necessary to protect Equestria, just as she had done to her own sister a thousand years prior.

"Do you mean that, Sunset?" she asked quietly. "Do you honestly believe what you're saying?"

The demon snarled angrily, right before she suddenly gasped and shut her eyes tight as if a pounding headache struck her. Taken aback by this sudden display, Celestia watched as the demonic alicorn struggled in her bonds, teeth bared in a savage grimace as some sort of internal battle took place.

Suddenly, Sunset's eyes snapped open, and Celestia was taken aback when she realized they were back to normal, the black receding like the tide. The demon's breath came in pained wheezes and gasps, and each word was like she had to force it out in a raspy whisper, a desperate plea for help.

"P-Princess...please...I don't...I'm not...a monster..."

Despite herself, Celestia's caution slipped ever so slightly.

"Celestia!"

An explosion of power shattered Sunset's bonds, so sudden that Celestia barely erected a shield in time, and even then it couldn't handle the full brunt of the released energy as it broke apart and left Celestia vulnerable to a magic blast to the midsection. Before she could even recover a ball of black lightning surrounded her form and bombarded her with a maelstrom of power, so fast and furious she couldn't even spare the concentration to erect another barrier.

"Ignore that little outburst," Sunset Shimmer growled triumphantly, eyes black once more. "I don't know what came over me. Some last shred of the pathetic mare I once was before the crown made me so much more? Oh well," she laughed as she increased the power of her attack, ignoring the pain in her horn as she turned the Princess of the Sun into a dark inferno. "I'll rid myself of it by finishing you off!"

The next thing Sunset knew was an incredible amount of pain to her nether regions as something slammed between her hind legs, so suddenly and so unexpectedly that she completely canceled her spell and instinctively curled inward to protect herself from another such blow. Deprived of the spell keeping her in the air and unable to maintain flight under her own power, Celestia began to fall, only for something purple to pop into existence, grab her, then wink out of existence again.