An Unforgettable Summer Sun Celebration
Celestia knew this day would come, but that didn't make it any easier. Seeing the twisted form of her sister standing in front of her with a twisted smirk and malice in her eyes made her stomach turn in knots.
"You know why I have come," the abomination spoke, her horn charged with a banishment spell. It wouldn't be as strong as what the elements could do, but that hardly mattered given what the result would be.
But she had to believe in her student now, believe that her mark of destiny really was tied to the elements. There was little she could do to protect herself from the alien spell.
"You'll not win, Nightmare," she faced the creature with her hardest glare.
"Oh I already have," they smirked back.
A loud bang rang out as the backstage door to Ponyville's city hall slammed open. Celestia's gaze turned in horror towards who'd interrupted them, while Nightmare Moon's spell flew wildly off course and pierced the ceiling.
"Ugh!" The newcomer exclaimed as they slowly trotted across the room. "I swear..." they mumbled.
Celestia's eyes widened as she took in the newcomer. It was a midnight blue alicorn with a flowing mane full of star constellations.
"L-Luna?" Her breath caught in her throat.
"No," they interrupted in what was clearly her sisters voice. "I don't want to hear it," they briefly placed a hoof on her chest as they passed her by.
"What manner of trickery is this!?" Nightmare Moon all but yelled while glaring at Luna.
Luna rolled her eyes. "Shut it, it's way too early for this."
"But-" Celestia started.
"No," Luna interrupted as she continued past her-- pulling the sound proof curtains aside --and out onto the waiting balcony. Where in which she grabbed the closest guard with her hoof. "You, get me some coffee, stat."
The poor stallion briefly met her eyes before running off, she wasn't sure who was more shocked, she or them.
Luna took a few steps back towards them before promptly sitting down on her rear. "This is the last time I attend one of Starlight's shindigs," she mumbled to herself.
"Sister, are you alright?" She eyed the two other alicorns.
Luna closed her eyes and raised one of her hooves. "I shall be fine, sister, I just need to get some caffeine into myself. More importantly," they turned their head and glanced at Nightmare Moon. "You forgot to mentioned to me that you were arranging a stage play. You know I wouldn't have minded fitting the role, as they say."
Celestia opened her mouth only to close it again.
"I don't care who you are, imposter," Nightmare moon started, the seething clear in her tone. "But I shall eliminate you as well!"
Luna just yawned. "Where do you even find these ponies, sister?" She asked while fixing her with a pointed glance while gesturing towards Nightmare Moon with her hoof.
"Enough!" Nightmare Moon yelled while lighting up her horn, taking aim at Luna.
Getting enough wits together, Celestia moved to intercept the attack, placing a golden shield barrier between herself, Luna, and Nightmare Moon.
It was over in a moment, but she was already panting from the strain of the attack. What was going on? Why were there seemingly two of her sister? She doubted that she could restrain another attack of that magnitude. Glancing backward revealed Luna sitting with her jaw wide open in the middle of a yawn.
"Please tell me you got better actors for Twilight and her friends at the very least, you know Rainbow Dash and Rarity will throw a tantrum if anything is even remotely off."
"W-what?"
Luna frowned, and she could feel the familiar weight on her head lessen as they levitated her crown over. They squinted their eyes and tapped it a few times.
"Is of good make... the props I mean," she put the crown back on her head facing the wrong direction. A moment later a frown graced her features.
"Please tell me you didn't dig up our regalia from the attic?"
"I- no!" She was quickly losing control of the situation-- assuming she even had any in the first place.
"I will not be ignored!" Nightmare Moon screamed as she reared up to charge them.
They didn't get very far before a pink unicorn teleported into the room. They took one glance at the situation before firing off a spell that froze Nightmare Moon solid in a cube of ice.
They galloped over to her sister and glared at her. "Do you have any idea where you are?"
Luna glanced about for a few movement before replying with a deadpan. "Ponyville's theater? They really upgraded it since last time."
The unicorn mare let out a load groan. "I told you, and the other guests, that the crystal was only for scrying, nothing else!"
"I really don't see what the big deal is," Luna replied with a flat look.
"You have no idea just when you are, do you?"
"Day of the summer sun," Luna replied as she lifted the coffee mug that the guard had returned with before downing it all in one go. She smacked her lips afterwards. "Should be just short of sunrise, shouldn't it?" She turned and glanced at Celestia meaningfully.
The unicorn smacked her hoof against her forehead.
"We're leaving," they said before dragging Luna away in her levitation field.
"Wait, who-" Celestia started only for the unicorn to turn around and blast a freeze spell in her direction too.
"Princess Celestia?"
She blinked a couple of times, returning from the memory. She levitated her tea cup and took another sip before replying.
"Sorry Twilight, I got a bit caught up in my own memories."
Twilight flashed her a smile.
"You asked me why I wasn't ever worried for Equestria, why I always thought things would work out?"
Twilight nodded eagerly; her becoming the sole ruler of Equestria hadn't taken away from her inquisitive mind.
"Well, you see..."
Author's Note
This was a fun one, I just had the random idea for it when I saw a Nightmare Moon picture.
I had to trim some of the fat to fit the story in under the 1k word limit, but hopefully it should still all be easy to follow. 
