“Luna?” A voice called, “Oh Luuuunaaaaa; Luna, wake up!” it continued.
“I...I fell asleep?” Luna asked, slowly coming back into consciousness. She looked about, but found no sign of anypony nearby. Thinking about it, she realized that the voice sounded like her sister's, but that wouldn't make any sense... perhaps Twilight had come to get something and woke her up on her way back out.
Luna noticed the faintest bit of sunlight coming in through a window. Shock ran through her: it was early dawn; she had slept too long! She threw the book in her lap off to the side and rushed out the door. She was galloping as quickly as she could, trying to reach the town square while Celestia was still there.
She burst through the doors of the pavilion, and immediately wished she had been less obvious. The scene she was welcomed by was fairly normal for the Celebration: Celestia was standing in front of her subjects, presumably about to give a speech. When she noticed Luna her face darkened, “Look who decided to show up,” she said, “I would expect someone as traitorous as you to try to hide.”
“H...huh?” Luna stammered. She wasn't sure what she had been expecting, but her sister looked frightening.
Applejack came forward out of the crowd, placing herself in front of Luna, “She ain't done anything!” she shouted.
Celestia's eyebrow rose, “Truly? You are covering for her? But Applejack, I thought you were the element of Honesty?”
“Celestia, what in the world are you doing? This is entirely unlike you,” Rarity said, placing herself by Applejack's side.
“Oh? What am I doing? What are you doing is more like it, aiding someone who wishes to tear this kingdom apart,”
“This is ridiculous! You can’t blame Luna; I don't really know what she's been doing, but you do not speak like that to my friends!” Rainbow dash said, joining Applejack and Rarity.
“Really, Rainbow? Your element is Loyalty, but you aren't even loyal to your ruler!” Celestia glared at the growing group of ponies, causing those in front of Luna to doubt whether their actions were worth making.
“N-n-now, st-stop that, Celestia!” Fluttershy squeaked, summoning every bit of courage and vocal strength she had. She joined the group, standing protectively in front of Luna.
“Wow, even Fluttershy feels strongly enough about this to show that tiny little bit of misguided courage she has,” Celestia said, seeming almost sarcastic in tone now.
“You know what Celestia, you're just being a big meanie!” Pinkie Pie shouted, jumping in with the others.
“My goodness, that's almost everyone, isn't it?” Celestia said, “Not that it matters, it's not as though you can physically block magic.” Her horn began to glow, and Luna became surrounded with a pink aura as her sister's magic enveloped her.
Twilight Sparkle was still within the crowd, shaking in fear and confusion. She couldn't confront her mentor; Celestia was always right, Celestia always did the right thing. “St...st...” she whimpered, trying to pull herself together and say something.
“Sister, you cannot be doing this!” Luna shouted, finding herself being levitated into the air. She tried to dispel the magic with her own, but her magic had not returned enough to match Celestia's.
“What punishment seems appropriate, I wonder?” Celestia mused, drawing out the tension, “Ah, I know, I'll let you think over what you have done for as long as you need...”
A collective gasp ran through the room, the horror on Luna's face amplified. “You can't mean...”
Celestia smirked. “Oh, but I do; I shall seal you away once again. It'll be another thousand years before you can come back.”
Twilight took a deep breath, her horn beginning to glow. “St...Stop!” she shouted, a blast of magic shooting forth, hitting Luna and dispelling the aura. Luna fell to the ground, accompanied by another collective gasp, Twilight followed by bringing a magical barrier around her.
Celestia's smirk increased even further in size, bringing her face to a maniacal state. “My my, even my very own protegee sides with the traitor? But...it makes no difference to me.”
“What do you mean?” Twilight's friends said together.
“I means it makes little difference to me who is sealed away,”–Celestia's horn began to glow once again–“if Twilight won't let me seal Luna, she is just as much of a traitor. So, I'll just seal her away instead.”
The magical aura began to surround Twilight now. As she began to levitate into the air, her confusion became horror. “No! No! You can't! Not you!” she screamed.
Rainbow Dash bolted towards Celestia, using her wings for added force and adopting a bullet-like posture. Before she reached Celestia, however, she bounced off an invisible shield that surrounded the Princess. She grunted, smashing back into the floor. She was too dazed to be able to stand again, but her ferocity had ignited her friends’ courage, and they all, even Fluttershy, charged in at Celestia. Even with their strength combined they all still rebounded off the barrier, futilely collapsing onto the ground.
Luna's horn was now glowing as she tried spell after spell, but each was suppressed by the her sister's magic, which was currently much stronger than her own. It seemed there was nothing she could do but watch in horror as Twilight rose to Celestia's face; suspended by her head, with her legs kicking at air.
“U...gh...st...” Twilight found herself choking, a black cloud beginning to surround her.
Luna couldn't allow this to happen. Her magic wasn't working, but there was one final thing she could try. She charged forward, leaving the barrier Twilight was still somehow able to keep together. She leapt forward at Twilight head-first. As she reached Twilight, her horn hit the barrier and tore through.
The spell had been broken again, and Twilight collapsed onto the ground, yet still Celestia showed no sign of concern. “So now it's you again, is it, Luna?” she said, once again lifting her sister into the air. Luna hung, accepting what would happen. The moment dragged on, the room hushed, before Celestia began to laugh, not a long evil laugh, but a genuinely amused chuckling. Luna was slowly lowered onto the ground, and Celestia wiped at her eyes with a hoof. “Oh, oh my, I got too carried away, didn't I?”
“W-w-w...” Luna said, words failing her, “What?”
The room was still, everyone frozen in shock, the shock for some fading into relief.
Celestia's face became serious yet again, “This was a test, you see. I wanted to be sure you knew the importance of selflessness.”
“But...this? You went this far?” Luna asked, her mind slowly beginning to comprehend what had just happened. As angry as she felt she should have been at her sister, the relief overpowered it to a much greater degree.
“Well, you said you wouldn't wait to return to your old position. I simply devised a plan to prove beyond all certainty that you are now completely free of evil magics, and, well...” Celestia paused, “...why don't we consider this an inaugural party, starting now?”
Luna found that her relief and excitement was such that; for now, she couldn't be upset with her sister. Later on, she realized just how crazy what had happened was, but it was okay, because she would have plenty of chances to get Celestia back with an even grander scheme in the future.