Possibilities

In purely magical terms, Luna had always been more talented than her older sister. Celestia knew how to make other ponies love her, and she drew strength from that love. Luna, for all her efforts, had never quite figured out that trick.

In the pre-dawn darkness, the fanfare of trumpets woke the princess from her reverie. The airship fleet was preparing to launch.

“Go now, my little ponies!” Her sister’s voice boomed over the assembled legions. “You know the stakes in this battle. If Discord cannot be stopped, all of Equestria will fall into chaos.”

There was a hint of tightness in Celestia’s voice. None of the soldiers would notice, but Luna and Tia had been together for centuries now. How could a sister fail to notice the inner workings of her heart’s twin?

The roar of thirty thousand voices answered Celestia, pledging themselves to the defense of the nation. Engines thundered to life, and the airships turned north. On the valley floor, legions formed ranks and fell into a steady trot. The two princesses stood, stiff and resilient, as their loyal subjects began the long march to war.

When the last pony had passed beyond easy sight, Celestia finally allowed herself a moment of weakness. She bent her head and gave a heavy sigh. “Are we really doing the right thing, sister?”

“Damn it, Tia. How can you still ask that? You, of all ponies.” Luna’s was surprised by the harshness of her reply.

“I remember a time when we thought he could change. When we thought he could learn to use his powers for the good of Equestria.”

“I never thought that, Tia.” Hadn’t she? Perhaps, for a time, but she’d been a different pony then. So much had happened in the intervening centuries. “You never understood him like I did.” That much, at least, was true.

Luna brooded as they made the long trek from the mustering grounds to Canterlot Castle. The pale glow that hinted at dawn crept across the horizon before them. Perhaps things with Discord could have been different. If the Elements of Harmony hadn’t been lost. If the Crystal Empire hadn’t fallen once more into shadow. If Fluttershy weren’t three-and-a-half centuries in the grave.

“If wishes were wings, we’d all be pegasi,” she muttered darkly.

“Sister, you know how much I hate to see you like this.” Celestia’s voice oozed with solicitous concern. “Somehow, this will all work out. I know it.”

It’s revolting, Luna thought. She needs to be harder than this. How can she defend our nation, when she’s not even willing to confront the hard truths behind Discord’s betrayal?

The thought pulled Luna up short. Celestia walked a few steps ahead before noticing her sister had stopped.

“You can’t, can you?” Luna’s voice was barely more than a whisper. “You can’t protect us.”

Celestia turned, and for a moment fear flickered across her face. “Please, sister, let’s go back to the castle. I know this has been a difficult time for you, but it will be over soon.”

“No,” Luna whispered. And then again, louder. “No. You’re just dodging the issue again, Tia. Dodging, like you always do. The truth is, you’re too weak to rule. I should have seen it months ago, when the first reports came back from the Crystal Empire. You were slow to act. You were afraid, weren’t you?”

Something felt wrong. Luna’s voice had taken on a deeper sound. She could feel magical energy surrounding her like a crisp, electric crackle, but she didn’t recognize its source.

“I’ve let this go on too long, Tia. Equestria can’t be trusted in your hooves any longer. Who knows what threats may follow, once Discord is dealt with. Who knows what else the Princess Regnant may be called upon to do. Your time is done, Celestia. Step aside, and I’ll see you’re treated with all the deference due a pony of your position. But leave the rule of Equestria to me.”

The look on Celestia’s face was not one that Luna recognized immediately. She might have expected anger, or confusion, or even that hateful fear she’d seen more and more over the past months. But Celestia’s eyes spoke of sadness and her mouth drew tight in determination. She looked... resigned.

“And what if I don’t step aside, sister?”

Luna gave a guttural laugh. “Don’t joke about this, Tia. You know I’m the strong one. You don’t want to fight me.”

“So you would bring civil war to our nation, at a time when our armies are off facing Discord – a plan you suggested, mind. Why you think a few legions can stop him when it took the combined power of the Ele—”

“Shut up! You know we can’t take that route anymore!” Luna’s own voice carried an undertone of panic at the mention of the Elements of Harmony.

“And who saw to that, sister? Who made sure the Elements could never be used again?”

Dark wisps of magic floated around Luna. She could see them at the edge of her vision. “It doesn't matter,” she snapped. “None of it matters now. Equestria must be strong, and that means I must be the one to rule! And if you won’t step aside...”

The pale light at the horizon shimmered, and Celestia stepped close, a tear trickling down her cheek. Her voice was very quiet. “And if I won’t step aside, you’ll force me away? You’ll leave the moon in the sky, and deny the sun it’s rightful place? Deny me my power?”

Luna quailed at her sister’s words, and at a sudden realization. She did know this magic that swirled around her. She’d felt it before, in a very different way.

“Yes, Tia,” she whispered. “Yes, I would.” Luna lowered her head in sorrow. “Do it. Now. Before it’s too late.”

Celestia reached out with one hoof and stroked Luna’s cheek. “I am sorry, my dearest sister...”

And then another magical aura took hold of Luna, cutting through the tendrils of darkness around her. A part of her prayed Celestia had the strength for this. There were no Elements to boost the spell's power, this time. Another part craved one final failure from the pony she’d called sister for so many centuries.

The darkness flexed and cracked. A small smile stole across Luna’s face. The right part of her desire would be answered.

“Oh, sister...”

The pony called Celestia had been warned, so very long ago, when she assumed her station. “The burden of the Night is heavier. You have all the joy and warmth of the sun. Your sister has only dreams... and nightmares. Past is prologue. Remember it well.”

She tried to tell herself it was necessary. She tried to tell herself that the moon wasn't such a lonely place. She didn't believe it.

Celestia’s breath hitched in her throat. Finally, her composure failed her and she sank to the ground of the grassy meadow where her sister had so recently stood. Tears fell, and were sucked away into the earth.

Her sister. Her only remaining tie to her old life. Gone.

Maybe, if she were very good, in another thousand years...

Her voice came out as a broken whisper. “Sunshine, sunshine, ladybugs awake...”