It was the eve of the Summer Sun Celebration. Princess Celestia had been very busy for the last couple of days. She had spent the entire day prior giving Mayor Mare of Ponyville very specific taskings for very specific residents of her town. The local orchard, Sweet Apple Acres, was to be in charge of the banquet. Resident fashionista, Rarity, would be in charge of decorations. The animal specialist would assemble a choir of birds. And the resident Weather Team pegasus tasked to the skies over Ponyville would receive yet another royal pardon to ensure her continued employment. As for the pink one... Celestia was certain that pony would find Twilight on her own. She seemed to have a knack for knowing when somepony new was in town. Everything was in place. It had been a busy day indeed. But it wasn't over yet. There was one last item that required her attention.

Princess Celestia laid out a parchment and took up her quill to send a letter to her most faithful student, Twilight Sparkle. She had given her some assigned reading for the summer break that would clue her in to the truth about Nightmare Moon. All that was left was making sure that all of the pieces were in the right place at the right time.

My dear Twilight, there is more to a young pony's life than studying. So I'm sending you to supervise the preparations for the Summer Sun Celebration in this year's location, Ponyville. (See attached Summer Sun Celebration Overseer's Checklist) And I have an even more essential task for you to complete, make some friends!

Summer Sun Celebration Overseer's Checklist
1. Banquet preparations at Sweet Apple Acres
2. Ensure that the local weather pony [Rainbow Dash] clears the sky of clouds.
3. Decorations.
4. Music.

"And now to just fire this off..." Celestia said. But just then a wisp of green smoke came in her window. It manifested into a scroll in front of her. She opened it and immediately recognized the claw writing of Twilight's dragon familiar, Spike.

My dearest teacher,
My continuing studies of pony magic have led me to discover that something really bad is about to happen. For you see, the mythical mare in the moon is, in fact, Nightmare Moon. And she's about to return to Equestria and bring with her, eternal night. Something must be done to make sure this terrible prophecy does not come true. I await your quick response.
Your faithful student,
Twilight Sparkle.

"At the zero hour, Twilight," Celestia muttered. "Alright," she said as she quickly amended her original letter and sent it off, probably responding faster than Twilight was expecting. But it no longer mattered. What was done was done. She needed to make her own preparations for what was to come.

Princess Cadance was enjoying a warm, morning bath at her villa in the Canterlot Palisades. A wisp of green smoke snaked in through the window. She looked up at a magic scroll appearing in front of her, landing on the small table beside the tub. It bore Princess Celestia's seal.

"Hmm, what does aunt Tia want now?" Cadance mused to herself as she opened the scroll with her magic and began reading.

Dear Cadance,
Please come to the Canterlot Castle as soon as you are able. As you know, I will be presiding over the Summer Sun Celebration tomorrow morning in Ponyville. While I am gone, I will need you to be at the Canterlot Castle in my stead until my return. You may tend to any minor matters that arise as you see fit. (Yes, you may finally sit on the throne if you please.) I have faith that you will do well with this assignment.

- Aunt Celestia

As she finished reading, Cadance threw her head back as she felt herself orgasm in the warm bath water. With a large splash, Shining Armor's head burst from beneath the soapy bubbles, coughing and gasping for air.

"Mmm, thank you, Shiny," Cadance cooed to her dutiful stallion. Shining wiped the soapy water from his eyes and looked at the scroll.

"What's that?" he asked.

"A royal summons," Cadance answered. "Aunt Tia is going to Ponyville for the Summer Sun Celebration tomorrow morning and I need to hold court at the castle for her tomorrow. She wants me to come to the castle now for, what I assume will be, a more detailed briefing."

"Oh. So we should get ready to go then!" Shining said, moving to get out of the tub. Cadance grabbed his horn with her hoof.

"Uh, ah. We have time. We can leave after."

"After what?" he asked. She smiled and pushed his head down.

"Deep breath," she said and she pushed him down beneath the water again. She grinned and her eyes flittered. She leaned back in the tub and moaned. Canterlot could wait a few minutes more.

In the small hours of the next day, Celestia waited backstage at Ponyville Town hall. She hated the Summer Sun Celebration. To her, it was an annual reminder of her failing her sister. But at last, it was her chance to redeem herself. As she stood there in the dark, she felt something that she hadn't felt in centuries: fear. She felt afraid and anxious. She had been preparing for this day for a millennium, for Nightmare Moon's return. It was only by the Elements of Harmony that she was able to defeat her the first time.

Or rather, she could have defeated her quite easily. But she was still her sister and she loved her. That was what stayed her hoof from a killing blow. It was only by the Elements that she was instead able to imprison her in the moon.

Celestia felt afraid. Not of Nightmare Moon. But of what she might have to do, herself. She didn't have the elements with her this time. She would not lose her sister to the moon for another thousand years. Celestia looked out the window at the moon. The mare in the moon looked back. Celestia prepared her suite of warding spells for the confrontation as she listened to Mayor Mare out on stage.

"Fillies and gentlecolts! As mayor of Ponyville, it is my great pleasure to announce the beginning of the Summer Sun Celebration! In just a few moments, our town will witness the magic of the sunrise and celebrate this, the longest day of the year! And now, it is my great honor to introduce to you the ruler of our land. The very pony who gives us the sun and the moon each and every day. The good. The wise. The bringer of harmony to all of Equestria: Princess Celestia!"

Celestia blinked. The mare in the moon vanished. In a puff of blue smoke, Nightmare Moon appeared before her.

"Hello, Nightmare Moon," Celestia greeted flatly.

"Goodbye, Celestia," Nightmare Moon growled.

Her black horn glowed a bright blue as she flung the spell at Celestia. The spell hit Celestia's invisible shield and several things happened. Firstly, time stopped. But not for Celestia. She reached out with her magic and studied the spell, expecting a standard death curse. Such spells were simple, and direct. But as such, they were easily countered.

But this was, instead, a spell similar to what the Elements of Harmony had done, set to banish Celestia to the moon for a thousand years. It was clear that it had taken her some time to construct the spell. Unsurprising given how much time she'd had in isolation. It was appropriate, Celestia felt. Her sister always did love to bring a sense of irony to a magic battle.

Celestia manipulated the spell. At its heart, Nightmare Moon's spell was a targeted teleportation spell. Celestia simply changed the location. As soon as she finished, she released the ward. With nary a blink of an eye, time resumed. Nightmare Moon's spell landed its blow and Celestia vanished. With victory in hoof, Nightmare Moon made her grand entrance in the Ponyville town hall to greet her new subjects.

Celestia reappeared standing in a cave, before the Tree of Harmony. Above her was the old castle she once shared with her sister. There could be no mistake, there was no turning back now. She, and the ponies she cared about, were now in harm's way. But she was a mare that played chess, not dice. She had done all she could to make sure that all the pieces were in place. She looked up at the Tree of Harmony. It bore the marks of Twilight Sparkle and the other five ponies that Celestia had found in Ponyville.

Celestia sighed. She was never one to believe in prophecy or fate. But now it seemed that it was time for fate to play its part. She had made sure to give Twilight her copy of Predictions and Prophecies, and her checklist that would ensure that she met the proper ponies. She was a smart mare. The trail of clues would surely lead her and her friends to the old castle and find the Elements.

Far away, in the Canterlot Castle, Shining Armor sat up in the massive bed. His military training had left him with an internal alarm clock that always had him waking up before the dawn every morning. He leaned over and disabled the alarm on the nightstand clock before it went off. He sat and looked out the east window.

"And here... we... go..." he whispered to himself, bracing for the first streak of the dawn's sunlight. But it didn't come. He looked at the clock again. It wasn't broken, or running fast, as far as he could tell. It matched the clock in the living room. The sunrise was late. "The sunrise is late," he thought to himself. "The sunrise is late," he repeated out loud, trying to wrap his mind around the absurdity of it. His eyes went wide as the realization hit him like a bucket of ice water. "The sunrise is late!" He was on his hooves with a start as adrenaline flooded his system. He quickly began to make a ruckus as he dressed himself. The other pony that had been sleeping beside him in the massive bed roused to the commotion.

Princess Cadance rubbed the sleep from her eyes and squinted blearily into the dark room as her guard pony fumbled with his uniform.

"What are you doing? It's not even morning yet," she groaned.

"Exactly!" he said, as he stumbled around getting dressed. "It's not morning yet, but it should be! The sunrise is late! The sunrise is never late. In a thousand years, the sunrise is NEVER late!"

"Shining, relax. I'm sure the clock is wrong or something," she said, rolling back over in bed. Shining finished getting dressed, put on his armor, combed his mane and put on his helmet. A few minutes later a knock came at the door. He opened it. Lieutenant Spearhead was on the other side.

"Your Highness!" Spearhead called into the room. "Princess Cadenza! You're urgently needed in the throne room!"

Cadance got up and out of the bed. She quickly ran a brush through her mane and tail, stepped into her golden horse shoes and affixed her tiara. Shining Armor had gotten specialized training in the Royal Guard academy. Cadance had gotten her own personal training from Celestia herself, in preparation to one day become a proper princess, in more than just title. The common ponies envied her, as a princess. But they would never know the pains of the great responsibility that came with the position when duty called.

And duty called.

"Give me a situation report, Lieutenant!" Cadance commanded as her emergency training kicked in. She walked beside him as he briefed her along the way. Shining Armor followed closely.

"We just received word from our pegasi express runners from Ponyville. Princess Celestia has vanished! The Mayor reported that she had arrived as scheduled, but when it was time for her to make her appearance, there was another pony there, calling herself Nightmare Moon."

"Nightmare Moon?" Shining asked, as they walked through the hallway. "But that's just an old mare's tale. Somepony is just using it as a scare tactic."

"It seems not," Spearhead said, motioning to the window as they passed. The three of them looked up at the moon. Its face was flawlessly white, devoid of the iconic 'mare in the moon' pattern. They moved a little faster. Spearhead rushed ahead and threw open the throne room doors for Cadance. Everypony in attendance quickly rose to attention.

"Give me an update!" Cadance yelled to nopony in particular.

"The Princess is still missing," Commander Herder reported.

"Locating Princess Celestia is our top priority," Cadance said. "Send a pegasus division to Ponyville to search for her."

"One is already on its way," the commander said. "But there is no knowing how long it will take them to find her."

"Then send two!" Cadance said as she took her place on the throne.

"What about the ponies?" another officer asked. "The rest of Equestria will be waking soon to dark skies. Ponies are going to start to panic." Cadance sat on the throne. Princess Celestia had always been fond of saying that their first responsibility was to the safety and welfare of their citizens.

"Send the second pegasus division to Ponyville to reinforce the search effort, and to spread the word about the... 'night-time holiday'?" she offered. "We need to make this seem intentional. Scatter Division Three to spread the word to every city we can reach as quickly as equine possible."

"A... Nocturne Appreciation Event?" an officer suggested.

"Yes. Excellent!" Cadance said. "Spread the word that we are doing a 'Nocturne Appreciation Event', and there is no reason to panic. The sun will be here soon."

"And if it isn't?" the commander asked.

"Then we will have far more to worry about than riots in the streets," Cadance said.

"But there will be no pegasi guard left in Canterlot," he said.

"The unicorn battalions will remain here," Cadance said. "But we need every speedy wing we have to spread the word. Make it happen, Commander! Immediately, if not sooner!"

"Yes Ma'am!"

"And what of this 'Nightmare Moon'?" Shining Armor asked. Cadance sat back in the throne and steeped her hooves together.

"If conquest is her goal, then she will move against Canterlot next. Against me. She may have gotten the drop on Celestia. But I will be ready." Cadance looked at her assembled team of Guard officers. "We will be ready. She will be stopped. And if she has done anything to Celestia," she growled, "I will have her begging to be sent back to the moon before I am done with her," she growled. Shining gulped.

Twilight and her new friends arrived at the Castle of the Two Sisters, deep in the Everfree Forest to confront Nightmare Moon. In the cave beneath the castle, Celestia waited for the sound of the Elements being used.

"You see, Nightmare Moon, when those Elements are ignited by the- the spark that resides in the heart of us all, it creates the sixth Element. The Element of Magic!" Twilight Sparkle said. The Elements of Harmony activated and a chromatic beam of magic struck Nightmare Moon. The alicorn screamed out in fear of being sent back to the moon for another millennium. But no such fate came. Princess Celestia took flight out of the cave, and up to the castle after the commotion of the Element's magic subsided.

"Gee, Twilight. I thought you were just spouting a lot of hooey. But I reckon we really do represent the elements of friendship," Applejack said.

"Indeed you do," Princess Celestia said, finally able to raise the sun, free of Nightmare Moon's influence. The sunlight poured into the window and she teleported herself inside the castle.

"Princess Celestia!" Twilight gasped as she trotted over to embrace her mentor.

"Twilight Sparkle, my faithful student. I knew you could do it," Celestia said.

"But you told me it was all an old pony tale," Twilight said.

"I told you that you needed to make some friends. Nothing more. I saw the signs of Nightmare Moon's return. And I knew it was you who had the magic inside to defeat her. But you could not unleash it until you let true friendship into your heart. Now if only another will as well," Celestia said, looking towards the blue alicorn amidst the broken armor. "Princess Luna, it had been a thousand years since I have seen you like this." Celestia knelt down beside the fallen mare. "Time to put our differences behind us. We were meant to rule together little sister," Celestia said.

"Sister!?" the other ponies gasped.

"Will you accept my friendship?" Celestia asked her. A thousand years was a long time. She had been so angry for so long. It had burned everything away, leaving her feeling so empty with naught left but her desire for revenge. Celestia knew this. She knew that violence would resolve nothing for her. And it would not fill the void that guilt had left in her own heart. Nightmare Moon had made herself Celestia's enemy by her hatred. But Celestia was wise enough to know that what she really needed in return was love. As she would often advocate, do I not destroy my enemies when I make them my friends? It was never more true than that very moment. Luna blinked back her bitter tears and jumped to her hooves to embrace her elder sister.

"I'm so sorry! I missed you so much, big sister!" Luna cried.

"I've missed you too!" Celestia said back as she held her.

"You know what this calls for?" Pinkie Pie asked. "A party!"

"Indeed," Celestia agreed. "We have much to celebrate!"

The eight of them walked out of the Everfree Forest to Ponyville.

"Princess Celestia!" a guard from the pegasi corps called out from above. "There you are! She's here! She's here!" he yelled. Immediately, two more pegasi joined him. "Your Majesty, are you okay!?" he asked.

"I'm fine," Celestia assured them.

The guard turned to his squad-mates. "You," he said to one of them, "fetch the Princess's chariot. And you," he said to the other, "get to Canterlot as fast as you can and tell them that we've secured the princess!" They both obeyed and flew off.

"And you, Sergeant?" Celestia asked.

"I'm not letting you leave my sight," he said.

"Twilight, why don't you and your new friends head back to Ponyville," Celestia said. "We'll be along in a short while. There is still a celebration for which you must prepare."

"Right away!" Twilight said with pride as she and the others trotted into town.

"Now what in the wide world of Equestria happened last night!?" the sergeant asked. Celestia looked at Luna beside her, and smiled.

"That, Sergeant, is a long story..."

Cadance and the rest of Equestria had watched the sky become bright with the dawn some time ago.

"So the sun is back," Shining Armor said.

"Thank you, Captain," Cadance said. "I'm glad I have you around in case my eyes ever stop working."

"Sheesh, somepony hasn't had her coffee," Shining muttered. A pegasus guard ran into the throne room with great haste, staggering briefly to catch his breath.

"Princess Celestia... has been found... safe," he gasped.

"... and!?" Cadance asked.

"And I was... told to tell you... as fast as I could..." he panted.

"That's... good," Shining said. "Crisis averted."

"I need more information!" Cadance demanded. "Where is she? What is she doing now?" A wisp of green smoke came in through the window and a scroll materialized in front of Cadance bearing Celestia's seal. Cadance caught it with her magic before it hit the floor and opened it. She read it quickly. "Princess Celestia is in Ponyville." Cadance reported from the scroll. "Carrying on the Summer Sun Celebration as planned with her..." Cadance read the last part three time to make sure that she hadn't gone crazy. "...with her sister."

Princess Luna watched as Celestia's chariot had arrived to collect her and her new... "guest". The smaller blue pony sat beside Celestia as the four pegasi guard ponies flew them into Ponyville to the joyous reception of all. Celestia had great practice with smiling for everypony. Even though she wanted nothing more than to just run away with her sister and just take the next month off to catch up on lost time with her, but as she always said, service to the citizens of Equestria came first. Luna was out of practice with wearing the happy facade.

They stepped off of the chariot into the center of town and two pegasi foals flew to Celestia with a flower lei. Celestia nodded them away toward her younger sister. The foals obliged and placed the flower necklace on the younger pony. Luna smiled weakly at the gesture, trying her best to keep her composure. It was all just so overwhelming. After a millennium in dark, silent isolation, it felt like sensory overload. Everything was so bright. There were so many ponies. And the noise! She just wanted to run away.

Luna listened as Celestia made a decree about the purple unicorn that had wielded the element of magic. Something regarding magical studies and friendship. Luna wasn't particularly paying attention. She was just anxious to leave. Celestia kept their visit in Ponyville mercifully brief. And after not too long, they were airborne once again, heading back to Canterlot.

Luna was happy to be away from the commotion of the crowd. Now there was only the sound of the wind rushing by, and the rhythmic beats of the pegasi wings pulling them. Luna looked down at her hoof when she felt Celestia's hold it. She looked at the alabaster alicorn beside her. Luna had to squint. Her fur was bright in the harsh light of day. Bright as the sun itself. Celestia turned and looked at her, and smiled. It was that same warm, patient smile that she always had. Luna released a breath that she didn't realize that she had been holding. The skyline of Canterlot came into view, perched on the side of the mountain. Canterlot Castle stood high above everything else.

"The main foyer?" the lead pegasus asked.

"East spire," Celestia replied. Luna's ears perked up. The guards exchanged nervous glances as they flew towards the castle. The chariot slowed to a stop beside the balcony of the 'Forbidden Tower'. One pegasus guard grazed the edge of it with his hoof and got a quick jolt of electricity from the surface. He quickly yanked his hoof away from the 'cursed tower'. Luna moved to step onto the platform, but Celestia stopped her with her hoof. Celestia's horn glowed, and a golden yellow spell spread out and washed over the spire, removing the several ancient defensive wards that she had placed on it.

Celestia stepped onto the balcony first, ensuring that it was safe to do so. Luna joined her as Celestia waved off the chariot. Luna grimaced at the state of it. The entrance from the balcony had been bricked up and sealed. Celestia's horn glowed again and the brick wall shimmered and evaporated, revealing the old entrance. Celestia's horn continued to work as she walked, peeling back each protective ward that she had place upon the structure. Each one was specially crafted and layered upon the others. Wards against monster attacks, magic, intruders, insects, and mice. Wards against moisture, dust, light, and even time itself. All of Canterlot could be razed and this tower would have been all that remained. When the last spell was lifted, Celestia opened the door and let Luna inside. It was Luna's personal royal chambers, utterly unchanged since the night she'd left a thousand years ago.

Celestia waited and watched as Luna walked through the familiar room, running her hoof along the surfaces of her furniture. Everything was kept perfectly preserved with immaculate detail. She saw her reflection in her vanity mirror. Her fur and mane were both lighter shades of blue than normal. She brought her hoof to her cheek.

"What is this now?" Luna asked of her appearance. Celestia blushed as she walked over to her.

"Some time after you... left, we encountered some Changelings, creatures that were able to change their appearance at will. I tried to replicate their magic, but I was unsuccessful. So I tried to use the Elements, but I was only able to slightly change my appearance. Like so," Celestia said, motioning to Luna. "I guess there was a bit of it left over when I put them away in the old castle. But don't worry, it will wear off in about a day or so."

"It's certainly different," Luna said, feeling her mane hang limp on her shoulders. She lifted her mane with her magic and tried to get it to wave again as it used to.

"That will come back in time as well," Celestia assured her, putting her hoof to Luna's. Luna looked up at Celestia.

"Thank you for... everything," Luna said. with tears in her eyes. "You have no idea how much I've really missed you."

"No, I do. I really do," Celestia said, wrapping her hooves around her. Luna brought her face closer to hers and kissed her. Celestia kissed her back. Luna kissed her harder, pulling her backwards onto her lush bed. Celestia kissed her again as they both opened their mouths. Their tongues slid over over on another as they ran their hooves over each others bodies. Each of them slid their hooves down between the thighs of the other.

"I have longed for your touch so badly!" Luna moaned into Celestia's mouth as she felt her sister pleasuring her. Celestia climbed into bed with her and straddled one of her sister's legs at an askew angle, bringing her pussy to bear against hers as they ground together.

"I'll never let another stallion come between us again," Celestia said.

Downstairs, in the throne room beside Princess Cadance, Shining Armor felt his ears become quite warm.