After Fluttershy is mortally wounded by a rouge bear, normal magic can no longer save her, and Twilight is not ready to lose her friend. She remembers a magic that could do things normally impossible: Alicorn Magic, the corrupting, yet potent magic.
After Fluttershy's loving spirit leads her to attempt to treat a bear infected with rabies, she is wounded to a point of no recovery. Angel Bunny found Twilight in her library and took her to Fluttershy, but Twilight was unable to heal her with her magic, and she was losing blood too quickly; she acted with what was her only chance: using Alicorn magic, the same dark energy that corrupted and consumed the normal unicorn King Sombra. The dark magic saved her, and with no side effects to Fluttershy. However, Twilight was driven to delve more into this sinister force that managed to save her friend and do what normal magic could not, once again. The taint of the magic began to seep into her, causing her to shun all normal magic and cast spells that were forbidden to use. Spike saw this unfolding and went to ask for help, but his pleas fell on deaf ears, as he was dismissed as being paranoid every time. He could not bring himself to return to her in that terrible state, so he left Ponyville in search of anypony who could convince her to give up the Alicorn magic before it was too late; little did Spike know, it was already far too late.
Twilight seldom left the library anymore, with all she had yet to learn about Alicorn Magic, how could she leave? Spike leaving was a bitter event, but it would all be worth I when she fully grasps this strange and unknown power. It had helped her numerous times before, even going so far as saving the life of her friend Fluttershy, a feat that her normal magic was not able to accomplish. She could help with her newfound power, or she could destroy. The dark thoughts in the back of her mind grew larger and larger with each passing day, with every new power she gained. It wouldn't matter what she had to do, she would still be helping in the end. Both her good side and the corruption nursed that thought, as it allowed the darkness to drive itself deeper and deeper into the very fiber of her being. These book told her to use her magic to do terrible things, things that she would have never dreamed of before; to eliminate anypony in the way of her power, and of her rule. For the first time she heard something other than her own thoughts, a knock on the door. Angered by the interruption, Twilight approached the door with irritation, with a pre-determined contempt for whoever was behind the door. When she opened the door, light poured into the pitch black room, and it made her squint to see who lie before her. After the blinding glare faded, she could see it was Applejack, with Spike next to her. "Twilight, little Spike here insisted that you are doing dark things in there, and that you aren't acting like yourself anymore", said AJ.
"I told Spike already, I am fine, and I am studying Alicorn magic. It saved Fluttershy and was able to change a potion we needed in order to help us save Equestria from Discord's old vines!" Twilight replied, annoyance in her voice. "Imagine the power I can gain, the spells I could do with its secrets..." something in the back of her mind made her say. "This isn't good for you Twilight. You sound angry, and nothing good can come of the same magic that King Sombra used to enslave and curse an entire empire for one thousand years! And Sombra was just a normal Unicorn when it took hold of him, I can't imagine what I would do to an Alicorn Princess like you." replied AJ. "Nothing good... NOTHING GOOD?! Plenty of good has already come of it from me! Sombra was weak, he let it take him, I am stronger, it is mine to command, not the other way around!" Twilight cried. Her eyes began to emit an eerie purple tendril; the purple tendril that Sombra also had. "Twilight, this isn't you, and I will not lose you to this dark magic; I will not LET you continue doing this to yourself!" Applejack yelled back at her. At that moment the corruption made its move. It came in full force to her head, seizing control of her. Applejack was an obstacle, and an annoyance; all the Alicorn Magic books told her to eliminate these thing in order to achieve what you can truly be, for limitation will only hold you back; friends were merely a limitation to her now.
In a black rush the shadows engulfed her, tainting both body and mind. The vile magic took to her far greater than it ever did to Sombra, and her new power surged through her. Her body grew in size, growing to be on par with even the massive Princess Celestia, and her horn darkened into a red point. Her eyes began glow green and her pupils shot red as blood. The darkness had made its move, and the old Twilight began to be suppressed. She tried to cry out for help, but all she heard was her own, terrible laughter. She slammed her hooves into the ground, and a spire of dark crystal erupted from the ground, impaling Applejack through the chest. As her friend whimpered, stunned and dying, the evil looked up and relished in its first work; the old part of Twilight screamed as she impaled her friend, but all that escaped her mouth was a wicked laugh. Her old self was defeated, and began spiraling down into the darkness she had let herself be overtaken by, never to return.
As blood gushed from her old friend's open chest, she stood smirking at the first work her new power had granted her. She spread her newly enhanced wings for the horrified onlookers to see as she began to cast her next spell. The spell rolled across the sky in a dark wave, driving out the light from the land, making shadows and light become indistinguishable from another. She then realized something was touching her. She looked down see a sobbing Spike clawing at her leg. "Let Twilight go you monster! Give me back my friend!" he was yelling at her. She raised him up on her leg and said "Oh, my number one assistant, don't you worry, everything will be okay, you are going to a better place" Twilight replied. She then put him back down on the ground, smiling gently at him, the corruption receding from her eyes. It was only for a moment, as a second later it came rushing back, and she raised her leg and crushed him underhoof with a guttural crunch. The ground was now stained with the blood of two friends, and Twilight laughed terribly at the evil she had created. Spike's death launched another wave of screams from the horrified onlookers as two of her closest friends perished at her own hand. She found their panic and fleeing amusing, so she sent of dark magic out of her to snag a couple of the unlucky bystanders by the neck and draw them back to her. "Are you afraid? I do not like cowards, you know." Twilight asked the two frightened mares. "No, I am not scared" squeaked one . "Me either!" coughed the other. "You should also know that I hate liars." Twilight said back to them with a smirk. They began to scream, which was cut off by a hard snap to the right. The lifeless victims fell to the ground, heads in a position not possible for anyone alive to have. "Such wonderful pain, I would love to bask in it longer, but I really do need to pay a visit to my lovely teach Celestia." she said with an evil grin across her face.
Twilight looked up at Canterlot and focused on her mentor through all the screams and cries, and teleported directly into Celestia's royal hall. "Hello Celestia, it was been too long since I have seen you. I learned a couple tricks while I was away." Twilight slyly said to Princess Celestia. "Who are you, and what are you doing in my hall...Oh no, what have you done?! Why are you bloody, I demand an explanation for this! Who are you, what have you done, and what are you doing here?" Celestia shouted back at her. "Oh Princess, you really don't recognize me? You think it would take more than Alicorn magic and the blood of my friends to make your own student completely unrecognizable. But then again, you always seemed very oblivious to what you didn't want to know." Twilight said with contempt. Princess Celestia stood up, her eyes widening, with tears starting to well up in them. "Twilight.... no... what is wrong with you? Why are you so tall? What happened to your eyes? And why are you covered with blood?" Celestia stammered. "Look, you disregard what you do not want to hear again. You heard me say where this blood was from. Say it." Twilight replied. "Your friends... but who, how, WHY?!" Celestia screamed at her. "Who: Applejack and Spike. How: a shard of crystal and a hoof. Why: Because they got in my way; you are in my way too Celestia." Twilight casually said back. "No, you will not hurt anyone else, and you will not take Equestia from me, or me from Equestra, I am ending this!" Celestia roared. Celestia launched a magic wave of light the knocked the tapestries from the walls and shattered all the windows. When the flash left, a dome of shadows as dark as pitch remained in the middle of the hall. When it receded into the floor it revealed the dark from of Twilight, her eyes glowing green through the shadow. "Surely you are going to give me a better challenge than that Celestia, or are you just angry at the artwork? To be honest, I never really liked it either." Twilight said as she crushed a shard with her old self on it. Celestia stood, shocked and angry. She conjured up a beam attack stammering "It isn't Twilight" and "I won't let the darkness win". She fired off a blast from her horn and Twilight did the same. Their beams clashed as they met, but Twilight's was stronger, and it began to push the beam of magical light back against the protector of the land. "If this is all you can do Celestia, I am shocked I have learned anything from somepony so weak. I will make a better ruler than you anyway, at least I am stronger." Twilight said as her beam crept closer and closer to Celestia. "I will not let you win, I forbid you to!" Celestia shouted back, and she drew upon her own Alicorn magic; Celestia's was weak and untamed, but it managed to move Twilight's beam back. "The thing is Princess, you can't stop me." She put more power behind her beam, and effortlessly drove Celestia's blast back to its source, knocking her back to the ground.
Twilight looked on her fallen teacher without pity, and lashed out shadowy purple tendrils to wrench her onto her back. Celestia looked up at her corrupted and merciless student and stammered, "You are not Twilight...You can't be!" the Princess cried out in anguish. Twilight walked up to her old mentor without flinching, and put her hoof on Celestia's chest and said "If it any consolation, Twilight is dead along with her friends. I am Darklight."she said coldly. She began to press down on Celestia's chest, not even batting on eyelash at the cries of pain coming from the helpless Princess beneath her. Her hoof cut into Celestia's skin, staining her beautiful white coat a terrible crimson. She continued to press down onto her chest, until she heard a piercing snap of a rib cracking, followed by a terrible scream of pain. She was continuing to press when she heard somepony yell "Get away from my sister!" Darklight was then struck in the back by a bolt of magical energy, pushing her to the ground. It was Luna's voice that she heard, so she stood back up saying "Ah, Luna, I was wondering when you would show up. Fashionably late as always I see; this was one party you couldn't afford to miss, however." Darklight said, looking back over at the broken and bleeding Princess Celestia. Celestia began to address her sister saying:"No... Luna... she is too powerful.. don't.." In the middle of her warning she was cut off by a shadow tendril piercing through her chest, driving straight through flesh and bone into the ground beneath her. Her final word was a weak and gagged "Run...", as she passed away. Luna screamed and began to draw upon the small amount of the Nightmare Force she still contained in her rage. "Just what I wanted." Darklight said grinning. As Luna began to transform back into the form of Nightmare Moon, she halted the transformation and drew the Nightmare Force to her. As it entered her body, she felt all the emotion Luna felt one thousand years before; jealousy, anger, sadness, and ambition. She drew upon its power, growing even larger than before, her mane dissolving into pure shadow, darker than any night. Darklight laughed as her teeth became jagged and she became even more powerful than before. "Thank you Luna, you gave me what I needed to secure my place in power; I reward anypony who helps me, sadly, the best reward I can give to somepony with the title of Princess is a swift death." Darklight said with a cold courtesy. At that moment she unleashed a vile pulse of energy, and a sickening slice echoed throughout the hall, as a splatter of blood shot from Luna's neck. Her head slipped off her shoulders, landing with a terrible thud on the ground, blood pooling around it. The look of complete disbelief still shown on Luna's face, even in death. "And now nopony can stop me. Not Celestia, not Luna, and I have even surpassed Discord in my power. This land needed a harder ruler, and the is exactly what I will give them." Darklight said as her began to laugh to herself.
