“Why!?” Twilight demanded, her right cheek roaring in pain. She charged up her horn as another blast lanced from Dawn’s, narrowly missing.

Please don’t make me say it again...I already feel terrible enough....

As Celestia powered up her own, Luna held a hoof in front of her. “Sister, we may not intervene.”

Dawn continued sobbing, in spite of the growing battle. Additional archivists came into the athenaeum and piled up everything they could onto carts, hurrying out once filled and returning with empty ones. Celestia scoffed at her sister, “And why not!?”

“Twilight and Dawn are the mirrors of each other. Two ponies, but only one soul between them. It is more of an internal conflict than an external one,” said Luna, as she ducked a ricocheted ray from Dawn’s attacks. A recently emptied bookshelf took the blow, breaking into a puff of dry rotted wood chucks, splinters, and dust. “Because of that, we may not step in, despite the circumstances.”

Dawn Twinkle continued crying, but managed some words. “It’s not r-r-right, that it c-c-comes to this. I’m sorr-r-ry, Twilight. I wish th-there was an-n-n-n-nother way....”

“How could this save or bring back anypony!?” Twilight hollered, popping another of Dawn’s shots with a negation-style counter spell.

Luna held up the note in her telekinesis. “Starswirl thought so. This hasty scrawling appears to be the last thing he wrote before he died, and he suggests that absorbing one’s other-world counterpart may be the only way to bring back others who’re gone because of a collapsing world.”

Can’t believe I’m doing this...what have I become...?

Twilight scoffed, “That’s lunacy!”

Luna craned her neck with a glare and flaring nostrils. “Hey! Watch your choice of words, Sparkle!!”

“Sorry, Princess Luna, it’s a—oh, enough!” Twilight yelled, narrowly evading a lightning bolt from Dawn.

She whirled around, sending a magenta spell in a whipping pattern. Dawn leapt to the side, but not enough. She yelped as it left a vertical cut on her left cheek. Dust fell from the ceiling. Every archivist stopped using so much caution and simply carried out the materials in telekinetic heaps as quickly as they could, getting the last scroll out of the previous closed antechamber. Luna sighed sadly, looking down, while Celestia looked at the fray with a growing expression of dread and panic. The embattled princesses now had opposing spell rays meeting halfway between them, both grunting, growling, and groaning. Ancient tile cracked under the strain, along with the floor underneath them.

Have I become like the very monsters I took down before the grey wave came? But this is my only chance....

“What would you do, Twilight, if our places were reversed?! Wouldn’t you try anything to bring them back!? Your friends, family, Celestia and Luna!?!” Dawn yelled, gaining some headway in the contest of opposing magic bolts.

“Not this!” Twilight screamed, evening the struggle. “I’d find some other way!”

“We tried that! Nothing panned out, or don’t you remember!?” Dawn retorted. The cracks in the floor spread. The widening crevasse edged toward them both.

“It’s still unthinkable! What could possibly drive you to this madness!?” screeched Twilight as she began to push through.

So begins the going around in circles...let’s see if this drives the point home.

Dawn disengaged, stepping to the side. Twilight’s spell shattered the far wall, exposing folded sedimentary beds, including an oolitic limestone. She gasped as Dawn seized her telekinetically, and threw her into the antechamber. She fired a pulse at the inner door, yelling, “Let me show you what’s left of my world, and maybe then you’ll understand!!”

The doors flew open, exposing the void beyond. Instantly an extreme wind pulled at everypony and everything. Twilight tried to escape, but was tackled by Dawn. Both ponies tumbled through the portal before Princess Celestia and Princess Luna erected a magical barrier at the antechamber’s outer doors, but even that bowed under the force. Both sisters continued pouring power into it. Celestia grumbled, “Are you still sure intervening wasn’t a good idea?”

“Might I remind you, dear sister,” Luna grunted through the strain. “I didn’t say it wasn’t a good idea to intervene. I said we may not intervene. There’s...rrgggh...a big difference.”

Out in the bizarre dark of the abyss, a shadow that did not diminish the colour of anything in relatively close proximity, spells rays shone brightly as they lanced betwixt the two junior princesses. Twilight and Dawn continued to flap about, their appearance, like a semi-transparent paint on a black canvas, glowed as a sharp accent against the deep darkness. Scraps of wood, tile, grout, and loosened oolites were swept through the portal in no particular order, nor in any clear pattern, and haphazardly floated in the warm nothing. Little sound came through the portal itself, though the timber groaned as it entered the empty limbo. Dawn shouted, “Welcome to Equus, Twilight! There’s nothing here! There’s nothing at all! What you see now, this void, is what’s left of my world! Do you like it? I don’t!”

“This, still, is not my fault, Dawn!” Twilight screamed. She winced as Dawn scored a glancing hit on her hindquarters. “What’s you’re doing is unfair to me, to Equestria, and ultimately to yourself!”

Don’t you even....

“Unfair!? You have the audacity to bring up fairness?!” Dawn squawked incredulously. “By even your account, Equus was further along the road of peace than Equestria! We had loyally served the gods, settled differences between all our nations, and starvation was all-but a memory, but we watched our world crumble, while yours, still torn by inequality and strife, fed off our destruction!! Now what is fair about that!?”

A fireball burst near Dawn, emanating from a magenta pulse. While she shielded herself, Twilight swung around and fired another volley. Dawn teleported behind Twilight, letting loose her own barrage. As she deflected the incoming attacks, Twilight yelled, “There’s no justification to deny another the right to exist!”

And here we go again.

“What should be, and what is, don’t coincide, Twilight!” Dawn answered, her tears starting anew. “Why should you get to exist, when I don’t!? What makes you more special!? What makes you worthier?! By your own admissions, we are equal!! I told you, I don’t want to do this, but I didn’t make the rules! The way it is, is the way it is! It’s not ideal, it’s not fair, but it left me with a choice! I had to choose one world or the other, and I chose mine! This is my only chance to bring them all back!”

Twilight grunted as she charged her horn. “You know just as well as I do that might doesn’t make right! It never has!! What would your friend say if they saw you acting like this!?”

Naturally, they’d be appalled, but in time they would understand, unhappily. Nopony’s arguing those points.

Dawn closed her eyes and sighed. She murmured, “Yeah, I know. Might doesn’t make right, and it won’t make me a hero, either. It just makes what is.”

Dawn opened her eyes again, leaking a large tear down the right side of her face. As Twilight frowned, the aura around her horn grew, and she growled, “Since that’s what you think....”

And so we come to the moment of truth. May as well get this over with.

Another such tear left Dawn’s eye as she fired up her own horn.

Above, Celestia and Luna dug their hooves in against the tugging of the void. The cracking of the tile from earlier provided a foothold, though the agony on their faces and the splintering sounding revealed what their hooves endured to keep them from falling in. Light flashed through the portal, bursts and beams of magenta and light blue. The sisters cried out in physical and magical exertion. Then through the portal came a glare, a harshly bright shine of the two colours in equal portions. For a tense half-minute or more, the overpowering light forced both sisters to squint in any hopes of seeing what was going on, or any hint of how the stalemate might end. The blue overtook the magenta for a moment, then all the light was the reddish purple. A moment later the glare subsided.

“I can’t keep this up much longer, dear sister!” Celestia whimpered.

Just then, Twilight Sparkle returned through the portal. She was fully opaque. Bracing her hooves against what was left of the grout and mortar, she blasted magic around the portal’s edges, and in a flash of white light it was gone, showing nothing but the damaged rock beds behind where it stood. All traces of its unique door jamb were gone. The sisters released the barrier. After a moment to alleviate the pain, Celestia slowly started toward her faithful student. Twilight flopped down, sobbing. Celestia slowed her approach. She looked down upon the junior princess. Twilight had her face buried under her forelimbs, sounding truly miserable. Luna followed behind at a few lengths’ distance. A few of the archivists timidly peered through the main doorway. Celestia tapped Twilight on the shoulder. Slowly she looked up at her mentor. Celestia pulled her into a hug, speaking in a soft, soothing maternal voice, “You’re okay, Twilight. You’re okay. You don’t have to worry about it anymore. It’s over.”

Twilight tightened her embrace of Celestia with tears still streaming down her face. She turned her head, nuzzling her right cheek against Celestia’s neck, leaving the vertical cut on her left untouched. She murmured, “It’s over. It’s all over now....”

Two weeks later....

Princess Twilight Sparkle opened the door to the Great Mausoleum. She beckoned her royal escort to wait outside as she entered, looking up and down the rows of names. She continued her slow amble like that for a good two minutes before coming to a stop. She stared in shock at large panel in front of her:

Starswirl The Bearded
B. unknown
D. 16th of March, Year 74 of the Age of Unity
“The greatest mind magic has ever known.”

She blinked several times in rapid succession for a moment, then plopped down into a sitting position without much royal poise. She mumbled, “Even interred, I’m still awestruck by you, by what you’ve accomplished.”

A moment passed in silence. A sunbeam shining through a higher window hinted at cloud movements in the skies above. She continued, “I didn’t want to come here, but I can’t think of any other way to get these thoughts off my mind.”

Another pause. She sighed through her nose, gazing around at the columns and the birds on the outside of the windows, flitting about. Twilight looked back at the name carved in the stone. “I’m glad you tried to save both worlds. I just wish you told somebody back then. Maybe then we’d still have both, instead of just Equestria.”

Twilight closed her eyes and hung her head. “We ran the numbers on your nineteen-scroll spell. You were right. With enough power, the two worlds would have been stablised. It’s incredible, that such a thing was possible. But as much as I want to, I can’t share that with my friends, or bring myself to tell them what all happened that day.”

Her eyes slowly opened. She rubbed at the healing cut on her left cheek. “Yeah…‘my friends.’ But are they really?”

She looked back at the great doors and saw they were still closed. “That’s the one thing you missed on. About absorbing her essence...I think that might have worked, if there was any of Equus left. But there wasn’t. It was completely gone.”

She tapped the floor unenthusiastically. “With Equus annihilated, absorbing her essence didn’t restore anybody. It just changed me into her. My memories are all that’s left of our world.”

The princess snickered for less than a second with a sad smile. “It’s kinda funny, that with a thought I can react like she would have, or like myself. Most of the time I’ve been acting as she would, just to keep from inciting confusion, or worse. I have all her memories, too.”

She frowned at the name on the tomb. “Guess I’m mad at you, that you botched your final piece of advice as badly as you did. Now I’m forced to live out her life instead of mine, or what I could have become in this world. And I’m stuck unable to say a word of the truth, without sounding like I’ve gone insane.”

She shook her head again. “Cannot be myself, but in truth cannot be her, either. I’m caught between day and night, stuck in this...crepuscular existence, where the only time I feel real is when I’m not quite asleep and not quite awake...and the rest of the time like I’m stuck in some mutation of reality, or like I’m watching a play or motion picture.”

The princess turned her eyes toward the doors again. “Maybe someday I’ll learn to accept life as Twilight Sparkle. But in my heart, home will always be Ponyton.”

Fin

Author's Note

And thus does she live out her days in the flesh of another. Twilight Sparkle, a prodigy of magical talent, and a princess who ruled with an even, just hoof, one who averted war without cowardice, and brought prosperity to the many. Yet there was always a melancholy about her, an incurable sadness everypony around her noticed, one that came after a certain eventful day....