Castle Of The Two Sisters: Throne Room 1000 years ago
"Not, another step!" Princess Luna stepped out from behind her throne, "Did you really expect me to sit idly by while they all basked in your precious light?" She the proceeded to the small balcony between the two thrones, "There can only be one princess in Equestria! And that princess... will be me!" She stomped the ground causing the entire ground to shake, breaking the balcony and cracking the wall until she shattered the window. Once that was done she raised the moon and then she was engulfed in a sphere of dark magic and once it dispersed her shape had changed; she was taller, her wings had a different form, the eyes she displayed looked like those of a dragon and her teeth became razor fangs. After her transformation she let out a maniacal laughter. She then used her magic to start destroying the castle.
Celestia flew up but was quickly forced to land when she was attacked by a magic beam that ended up destroying the ceiling revealing the moonlit sky. "Luna, I will not fight you! You must lower the moon! It is your duty!"
"Luna? I am, Nightmare Moon! I have but one royal duty now: to destroy you!" She then shot a beam of magic that was quickly dodged by Celestia by flying upwards into the sky, "And where do you think you're going?" She then took to the sky as well and continued to shoot beams destroying even more sections of the castle. Eventually she landed a hit on Celestia causing her to fall to the throne room while she laughed away at her opponent.
However, Celestia was not about to give up and she got up. "Oh, dear sister. I am sorry, but you have given me no choice but to use these." She used her magic to activate a panel on the floor that revealed the Elements of Harmony. She took them with her magic and wielding them she stood up against Nightmare Moon.
Upon seeing Celestia using the elements, Nightmare Moon drew all her magic and shot a blast of magic against her. But Celestia, in tears, counterattacked with the power of the elements.
The elements easily overpowered Nightmare Moon's magic and once both energies subsided the elements fell to the ground. However when Celestia looked up she saw: not Luna, not a statue like Discord; but Nightmare Moon and next to her an orb of magic. "Did you really think I would not be prepared for that trick? Now I hold in this orb the power, not only of the magical blast I just used, but the power of the elements as well." She then applied magic on the orb causing all of the power stored within it to be shot straight at Celestia.
The alicorn tried to defend herself but the pain from the magical beam shot at her, plus the burden of using the elements (that were clearly made to be used by more than one pony at a time) all by herself, had taken its toll and she could do nothing but take the power of the orb. And just like that, Celestia, disappeared.
Nightmare Moon returned triumphantly to the castle and there she noticed the elements had turned into stone spheres, probably due to the fact that they had just been used in the unintended way of channeled through a single user. There was nothing that could stop her; but something was wrong, the moon had a different vive to it and when she looked up she noticed that the moon now had a crescent shadow in the shape of a mare, "Celestia. Of course, the elements are not a force of destruction."
Suddenly the doors of the castle opened revealing Star Swirl and all the royal mages. "Well, well, well... Star Swirl. Why are you here? Heve you come to defy me?" Star Swirl scanned the room looking for Celestia but no luck. "If you are looking for my sister, she has already been defeated. Don't believe me, then look up at the moon." All of the mages turned their eyes to the moon and witnessed the new shape that had appeared on it. "She has been imprisoned there. Anything to say Star Swirl?" The old unicorn simply remained silent. "Thought so." She then turned to the rest of the mages. "And all of you, what have you got to say for yourselves?"
One of the mages stepped forward and spoke, "We followed elder Star Swirl when he told us Princess Celestia needed our assistance, but we knew nothing of the situation."
Nightmare Moon glared at the lead mage, "Leave, Star Swirl, as of now you are no longer part of the royal mages and you permit for spellcasting anything other than the basic levitation spell is officially revoked."
Star Swirl, admitting defeat, simply lowered his head and walked out the door stopping right outside. "On the thousand year, the stars will aide her escape." And after that he was only seen entering his home only to come out for his funeral.
Nightmare Moon did not oppose him for that, after all, that was not a threat, he was only speaking an undeniable truth, it was a warning and if anything, it would only help her.
After Star Swirl was out of sight Nightmare Moon was left in the beat down castle with the mages and explained the situation, eventually she was approached by the youngest of all of them, "Excuse me, Princess." She calmly responded by turning around and putting up a stoic face. "I understand why you raised the moon out of time, but if the moon stays up forever, the flora will not survive and by consequence Equestria will perish."
Nightmare Moon closed her eyes and analyzed the situation, after all, that much was true. When her eyes opened she lit up her horn and lowered the moon." This is what will happen, all mages will still be free to work on their projects but you all must also work on making sure Equestria can survive night eternal, and in case you think of not making any progress on purpose then remember, whether you succeed or not, eternal night will come, so all of you are to return to Canterlot and do as you must." She then turned to a young male mage. "Diana," the aforementioned had a regal-black mane and tail, turquoise fur and lavender eyes; his cutie mark was crystal in the shape of a five pointed star glowing like an aurora, "did you manage to finish the crystal communication system?"
"I have, Princess."
"Good. Prepare it for tomorrow, I will give the statement of today's event first thing at sunrise tomorrow. Make sure to send messengers so the town leaders know what's happening."
"Will do. And thank you for making my project possible, when I did a request with your sister she refused without reason."
"She had a reason, but her worries had no reason to be. She feared progress and refused it if it brought upon a bad memory. Somepony like that should not rule."
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Canterlot Palace Next day
All the ponies had gathered at the palace balcony where they would receive an explanation of yesterday's events, and so would every settlement in Equestria since all of them had equal gatherings at their main plazas. Eventually a crystal began glowing and one alicorn stepped out to the balcony, but it was one they had never seen before. "My subjects, you may be wondering who I am, well, I will tell you; I am Princess Luna. Perhaps you failed to identify me due to my appearance change, but all will explained soon." In Canterlot nopony noticed, but the crystal was transmitting the message to all of the land. "Yesterday my sister and I were forced to battle against each other with I standing victorious. But worry not, as this will not change much from the lives you have lived up to this point, but there will be changes nonetheless." This caused some fear amongst the civilians. "First of all, and I assume it was obvious, there will only be one princess from now on and it shall be me. Second, to avoid this event repeating itself, until I see it needed you will refer to me by my battle name: Nightmare Moon." These statements eased the citizens, after all the only change was the one of Princess Nightmare Moon. "Thirdly, Canterlot has been our capital for quite some time but the castle that hosted the throne has always been in its current location so given the fact that it is to much of a hassle to travel from the castle to the palace for any thing that is not court and the fact that it has suffered heavy damage from yesterday's battle, I decree that Canterlot Palace be turned in to Canterlot Castle." And with that all fear that had originally been formed within the crowds disappeared. "Fourth and lastly, every ten years; day will be cut shorter by one hour so that in 120 years days will be no more. The royal mages have begun preparations so that this change does not cause trouble to our land. That will be all." She then returned without another word to the place without another word. The crowd had mixed feeling about the last announcement but the odd thing was that, due to the previous ones, none of them had fear.
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Canterlot: Castle Courtyad 880 years ago
Today marked the last 'Night Crown Celebration' that would have a sundown as part of their schedule, today would begin the eternal night. Almost an hour ago, the Princess raised the sun for the last time and the festival began; but now everypony was gathered at the stage that had been set for the celebration.
Eventually Princess Nightmare Moon stepped up to the stage and the crystal communication system (or CCS as most often called it) activated. "My subjects, on this 'Night Crown Celebration' we mark the beginning of a new era in our history, today we enter a state of night eternal. We must all be thankful to all of the royal mages for making this possible and now I will lower the sun and lift the moon so it holds it's rightful place in the sky" The crowd cheered at their ruler's words, and as she lit her horn with her magic and brought upon sundown the cheers grew louder. Nightmare Moon could not believe it, an event feared two centuries ago was now being acclaimed. Eventually sunset became twilight and finally the whole land was covered in moonlight.
From then on the party was really at it's peak and the Princess watched from her balcony alongside an old stallion by the name of Diana. "I'm glad I got to live to see this day, I just wish Twilight Sun had been here to see it with me."
The princess looked at the mage that had replaced Star Swill as head mage, his friend, his confidant. "Time always claims the lives of the ones we car about, everyone dies eventually, even beings like me with eternal youth can die and will die eventually by one reason or the other." The frase thought true had changed the mood so she decided to change topic. "How is your daughter, Twilight Song?"
"She recently had a daughter, Twilight Moon. She tells me the foal has lavender eyes like her grandfather."
Nightmare Moon smiled at this. "Your a lucky stallion Diana, but I must ask; why did you marry a mare with the tradition to name their first born daughter 'Twilight'?"
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Canterlot Castle: Princess Bedroom 500 years ago
Court had just finished and Nightmare Moon had retreated to her bed chambers to meditate something that had come up in her mind a few days ago. 'Should she return to being Luna?' The thought came up when she noticed that the magic that once changed her eyes and teeth was no longer taking effect and they had become just how they were before the battle with Celestia. Eventually a maid informed her that dinner was ready.
The ones that held their meal at the royal table were the Princess, group heads, guard captains when the situation called for it and the occasional guest. Tonight it was just the Princess and head mage: a unicorn named Dark Crow; a rather unfitting name since he had royal-blue fur, velvet eyes and the only black trait he had was his jet-black mane, his cutie mark was the outline of a cat with a witch hat.
Their meal was quiet one but it didn't stop her from think at the fact that the pony in front of her trusted her and was completely loyal. She didn't need to scare him into doing what she wanted. Ponies all over Equestria now saw her as somepony different. "Crow," The mage looked up when his name was called, "I have an announcement to make later before the end of the hour cycle. Please, prepare the CCS when you have finished with your meal."
After the unicorn was done he retreated and did as instructed and one hour later Nightmare Moon was ready to speak to her kingdom. "My dear subjects, as I once said five hundred years ago I would go by my battle name, Nightmare Moon, until I was sure fear was not necessary to maintain peace and so now I hold to that promise. I will once go by the name of Princess Luna." When her statement finished she used her magic on herself causing the colors of her body to return back to normal.
And thus Nightmare moon was no more.