In her tower in the Castle of the Two Sisters, Luna took a much needed break.

There had been no petitioners or royal duties needing her immediate attention, but that didn’t mean that Luna didn’t want some time to herself now and then. Mostly so she could collapse in a sleep-deprived heap and nap. Almost entirely to nap, in fact.

At a little under six months old, Twilight Sparkle may have been a constant source of joy, perhaps the only source of joy in her life, but Grogar’s Testicles was her new foal exhausting.

She supposed it was a blessing that Celestia had stepped up to the role of nanny with an unrestrained enthusiasm that was nearly contagious. During the few months leading up to Twilight’s birth, her older sister had doted on her; it had almost felt like the old days, back when they were fillies. Of course, neither of them were now, but seeing Celestia care about her, seeing her put in the effort, it chased the dark thoughts away.

There were a lot of those, even these days.

At Luna’s request, they had kept knowledge of both her pregnancy and her daughter to as few ponies as possible. Celestia, mercifully, had taken the promise seriously, managing to keep the filly’s existence well hidden. Luna herself had admitted that both of them were being pragmatic with that; after all Twilight’s birth had brought forth a lot of questions regarding the future of Equestria as a nation: She was a princess, but was she a crown princess? Was there even a line of succession? She was just a (presumably) mortal unicorn, and there were still noble houses that would see her as some sort of political pawn, too many hypotheticals and questions that would need clear answers.

Grand endeavors had to be undertaken and sinister plots would have to be unraveled. In time, both sisters had agreed, Twilight would be introduced to her kingdom. But for now there was no reason to risk the filly’s childhood innocence for some courtly whims.

Finally shaking off the aura of sleep, Luna got to her hooves. Some days it was hard, waking up and not finding herself curled around the familiar warmth of her Fool. Some days it was easier. Twilight helped. Twilight being there always helped.

She had his eyes.

Stretching her wings, Luna glided across to her sister’s tower, stomping down a tiny, tiny flash of jealousy at the fact that it was slightly taller than hers. Let Celestia have the taller tower, let her have ponies arguing over cow ownership.

What Luna had mattered far more than any of that, even if it was currently babbling between Celestia’s forelegs at an open book. Her sister looked up as she flew in.

“You’re looking far better, little sister.”

“Indeed? Perhaps the infant’s penchant for napping holds a deeper wisdom. A brief moment of slumber does wonders,” Luna smiled as her daughter looked up from the book, tiny purple face lighting up as she struggled out of her aunt’s grasp and toddled over to the dark alicorn, continuing to babble.

“And hello to you too, my little star. I hope you have not developed a sudden sense of mischief in the brief time I have been away?”

“Hardly,” laughed Celestia. “You put a book in front of her and she’s as happy as a lark. I think she was trying to read it to me.”

Luna eyed the text that Celestia had picked out, raising an eyebrow. “The Ponyynich manuscript? I was not aware that it was possible to read that at all.”

“It’s one of the few I could find that had any pictures. But who knows?” Celestia leaned down towards her niece, letting loose a puff of air and chuckling as the filly fell backwards, squealing in delight. “Perhaps she’s naturally a brilliant scholar, the kind that would put even Star Swirl to shame.”

“I would certainly welcome a magical prodigy into our midst,” Luna smiled. “So many books in the castle library go unread, surely they are secretly crying out in despair for a fresh new face to appreciate them.”

“I’m sure they await their new lady and mistress with unrestrained anticipation,” Celestia sighed, “Truly, I envy you sometimes Luna.”

“Envy?” Luna raised an eyebrow as she scooped her daughter up, bouncing her gently. “Evidently you are unfamiliar with the rigors of childrearing, Tia.”

“Perhaps I’m not envious of the sleepless nights or soiled diapers, no,” Celestia admitted. “But to have somepony need you so utterly, to nurture them and watch them grow and discover the world around them. There’s something… there’s something to it.”

“Do you not often say you see all of Equestria as your children?”

“Luna please, half of the petitioners are old enough to be our grandmother. That’s just a silly princess platitude to calm the masses,” Celestia wrapped a wing around her younger sister.

“She’s beautiful, you know. Your brilliant little star.”

Luna sat here, regarding Twilight. Her smile faltered a little bit. Celestia wrapped her wing tighter.

“I know he’s not here Luna. But we’ll be there for her. She’ll have a wonderful life.”

“...Promise, Tia?”

“I promise.”

Daughter safely in her custody, Luna shut the door to her bedrooms gently. Twilight wasn’t asleep and was (perhaps unsurprisingly) a heavy sleeper besides, but she was also at the age when too many things excited her. Luna sometimes had trouble keeping up with her daughter’s magic energy.

She smiled. At least the magic surges had stopped.

Smiling. Laughing. Little by little, she could climb her way out of that pit of dark thoughts. She had grieved over Peritwinkle, she always would, but the weight of parental responsibility was comforting. She felt, in a small way, complete, and it was all thanks to the little bundle of fuzz and babbling that was laying before her now. Twilight turned towards her mother, regarding her with those big innocent eyes of hers before coughing openly into Luna’s face like most infants were inclined to do.

“Manners, please, my little star,” Luna turned Twilight around and placed her between her forelegs, hooves hugging her daughter as the filly wiggled about. “A princess does her best not to cough in another pony’s face. There are more subtle ways to let one know one’s displeasure.”

But instead of laughing at her mother’s hilarious joke, Twilight just continued to cough.

And cough.

Panicking, Luna scooped her daughter up again, turning the foal over, ignoring her fussing as she to make sure that Twilight wasn’t choking or worse.

“Twilight? Twilight!”

Hearing her name, the filly stopped squirming and coughing, looking back up at Luna. With one final chuffle, she spat something fuzzy out and giggled happily as the whatever-it-was fizzled in the air.

It was a single black rune.

No.

No.

It wasn’t contagious! It’s not contagious! She knew it wasn’t. It wasn’t possible.

Luna tried to stay calm, tried to do anything to avoid a panic attack. It wasn’t possible. It wasn’t right.

Luna looked deep into Twilight’s eyes. The infant princess just looked back at her, tears welling up. She didn’t understand what was happening, but if her mother was scared, then obviously, she should be scared too.

It wasn’t fair.

Maternal terror gave way to righteous anger. If the universe thought it could take away the last living light of her life, it had another thing coming. Luna wasn’t the naive filly she was a year ago. The loss of her Fool and the gain of her daughter had transformed her. She had experience, she had resolve.

And most importantly, she had a List.

Twilight on her back and horn blazing with pure motherly fury, Luna summoned forth her almighty List; the vast library of hypothetical parental situations she’d worried herself sick over.

At this point it was more of a tome. It had an index. And it was leather bound.

Opening the pages and flipping towards the back, Luna's eyes desperately scanned the scenarios and solutions she had put forth, unwilling to waste even a moment of Twilight’s health.

Plasmoid invasion? Irrelevant. Potential undead suitor? Too early (though she had a wooden stake sharpened as an early precaution, just in case).

Ah! There it was. Plague of Unknown Origin. Instead of a detailed solution, there was just one word written in:

Panacea.

Of course.

Wasting no time, Luna swirled magic around herself and her ailing daughter, blasting away to her distant desert sanctuary with a familiar clap of teleportation magic. Past the door, past the traps to keep out wayward bandits, into one of the few places left in the world that could be considered safe.

She threw aside the bed, the unfinished projects, the sketches, even the books, until finally she had found the small device she had been looking for.

It hadn’t been something that could have saved Peritwinkle; even if she had managed to find a magic source large enough to power a pod of that size, she hadn’t had the materials or time to build one.

But she managed to restore one. Now, for the first time in millenia, it’d serve its purpose.

“Shhhh, hush now little one. It will be alright,” Twilight squirmed and sniffled as her mother gently unfolded the Panacea, hooking up rune after rune and finally placing the filly inside. Nuzzling her until Twilight quieted, she gave her one last reassuring smile, and activated the pod.

Arcane thrumming filled Luna’s ears as the pod slowly ascended, lights flickering as the magic was sucked out of it. It’d take a few moments to prime the spell, but once active it’d tease the plague out of Twilight, healing her while she slept peacefully.

It was okay. Twilight was okay.

With the crisis averted, Luna found herself drained. Exhausted. Panic had sapped her strength almost down to nothing, and she leaned against one of the station’s pillars. Watching the Panacea float in midair with Twilight gently slumbering inside, she began to cry.

She had almost died. Her baby had almost died. And it didn’t make any sense! Luna knew magical ailments like these weren’t contagious. Any sort of terminal arcane illness like this only came from direct exposure to dark magic.

But where in Equestria, when in Equestria, would her daughter have even had a chance to face something like that? She had been careful to make sure all of her research projects had been separate, and for the plague to progress as fast as it had, it’d take an enormous dose of thaumic radiation to begin with.

It couldn’t be another pony could it?

Could it? No. This kind of cursed magic hadn’t been seen since her and Celestia had faced down Sombra years ago, and they had…

Then it hit her.

Celestia.

What pony had been fascinated with Sombra’s spellwork after their confrontation?

What other pony had spent any time around the Royal Fool, besides her?

What other pony had that much arcane power?

Which pony had spent the day with Twilight?

Which pony had just said she envied Luna?

“No…” Luna whispered to herself pressing her head into the wall, trying to banish the familiar dark and awful thought. “She promised she’d be there. She promised she’d help. She’d never do something like—”

Never do something like this?

Like the way she hadn’t swooped in and claimed the love of Equestria for herself and herself alone? Like she hadn’t starved Luna’s court of petitioners? Like she’d hadn’t taken away every single other thing in Luna’s life? What were a few more ponies on top of everything else?

A rushing feeling drew her out of her spiral. She looked up as auroras of color danced around the Panacea above. Evidently it had absorbed enough magic to begin the process. Inside, her daughter slept peacefully.

Her daughter. Forget Equestria, forget her Night Court, forget… Peritwinkle. Twilight was what mattered. She’d survive this, she’d be okay, but what about the next time?

Would she really risk Twilight’s life on the off chance that this was all some terrible coincidence?

No. It was clear that so long as Celestia was around, so long as Celestia’s sun hung in the sky, her daughter wouldn’t be safe. She’d never be safe.

Luna stood up, steeling herself as she made up her mind, letting that dark thought finally take over. She knew what she had to do.

Taking one last look at her daughter above her, Luna went to reach out for the foal, hesitated, then stepped back.

“I will be back for you, my little star. I swear it.”

Wings flaring, horn glowing, Luna teleported away. She had a kingdom to claim.

What had she done? What had she done?

The aura of the Elements of Harmony faded, depositing Celestia on the grounds of the castle. Even with Luna… Even with Nightmare Moon gone, the full moon hung in the sky accusingly, now stained with the sin of her victory. The elements clattered to the ground around her. Somehow, she knew she’d never be able to use them ever again.

“Your Highness? Your Highness!”

A pair of guards came rushing up to her, relief on their faces as they carried another guard between them. He seemed to have been hit by something.

“Captain, I need you to gather the staff, I have a—”

“There’s no time, your majesty! Who was that? Was… was that Luna?”

“What do you mean there’s no time? And at ease, captain, I’ve… dealt with the problem.”

“Your battle took down most of the castle! The south tower’s been hit and the bridge to the north tower’s been destroyed! The main halls had most of their support pillars taken out too! We’re trying to evacuate everypony as fast as we can, and that includes you!”

“How many are injured?” Celestia tried to cling to that familiar bit of organization and leadership that, right now, was the only lifeline she had. “Are there any dead?”

“We’re not sure of the number of injuries, Your Highness, but there appear to be no deaths so far,” the guard grimaced. “I wish I could say the same of the castle. We need to leave, now.”

Still dazed with grief, Celestia blinked slowly, trying to process something the guard had said prior. The south tower going down meant she had to evacuate her staff out of her bedrooms. But the north tower would be—

“Twilight!” she screamed in horror.

“Ma’am? Wait, your highness, you can’t go there, the castle’s coming down! Princess Celestia!”

But Celestia had blasted off as fast as her wings could carry her, charging towards a tower that even now, was shifting under the weight of post-battle stress.

The guards had underestimated how much damage the sisters’ battle had wrought. The whole castle was crumbling to pieces around her; the south tower had already collapsed entirely and the north had little time left in the world as an intact building.

Of course fate would have it that Luna’s bedrooms would be at the top of the entire damn thing.

One more flight of stairs, one large door to burst through. Celestia wasted no time, tearing down a tapestry in the back, horn blazing as she threw open the heavy door, shattering any lock on it in the process.

The nursery beyond was empty.

“Twilight? Twilight! Twilight!” Celestia looked about frantically, even as the tower lurched and threw her about. The entire thing was coming down.

Throwing up her magic, Celestia tried to stay calm, casting a spell as far out as she dared, scanning the tower. There were no ponies inside save her, thank the stars. The guards had managed to evacuate most of Luna’s staff. Or what had been Luna’s staff.

But that meant no Twilight. And that meant that any attempt at staying calm was now thrown completely out the window. Celestia began tearing the nursery apart, ripping up what she could. Luna must have hid her daughter away, did she expect this much collateral damage? But she had to have left behind some clue, maybe?

An unfurled scroll caught her eye as another stony groan reverberated through the tower. Trusting her gut, Celestia grabbed the scroll and jumped out the window, giving a brief look behind her as the entire roof caved in, followed by the floor, and the floor below that one.

Luna’s tower collapsed.

Celestia sat in the ruins of her life, oblivious to the various courtiers and guards barking orders around her. Miraculously, nopony had died in the destruction, though a few injuries had been reported. Celestia hadn’t been paying attention.

Luna. Twilight. In one night she had lost her entire family. And somehow, it felt like it was her fault.

No, she hadn’t lost Twilight. Twilight wasn’t gone, she had to believe that her niece was out there. Finally unfurling the scroll she had braved the northern tower for, she looked it over. It wasn’t a missive or some diary entry like she had hoped, instead it appeared to be a series of drawings. Technical sketches and notes on a small cradle of sorts, as well as the detailed spellwork powering a… healing enchantment?

Recognition lit up Celestia’s eyes. A Panacea. She hadn’t seen one since… Well she certainly didn’t think any of them were left. Clever Luna, of course she’d have managed to get one working again, it’d have been perfect for Twilight.

Pain, a deep aching pain, stabbed at her heart. Her baby sister was on the moon now, no thanks to her. How could she not have seen what was happening? How could she let things get this bad?

Ponies talked around her, discussing plans, taking inventory of some of the few artifacts they were able to recover from both towers, whether to rebuild the castle or move it entirely (Celestia caught snippets, something about a mining town near a mountain that’d be ideal), all around her life seemed to go on, as if Equestria wasn’t missing an entire princess. As if Celestia wasn’t missing half her soul.

But there was still a ray of hope left. If Twilight was inside a Panacea, she’d be the safest pony in Equestria. And more importantly, she’d be absorbing a massive amount of magic, enough to be something that a trained pony could detect.

Celestia could do this. No matter how long it took, she’d track down her niece. Even if it took a hundred years, even if it took a thousand.

She looked down at some of the possessions they’d recovered from Luna’s tower: Jewelry, books, a few spare tiaras. Little left to indicate the family members she’d just lost.

She’d failed Luna, she wouldn’t fail Twilight. She had promised.

Author's Note

Might be a delay on some of these last three or four chapters coming in, sorry.

Thanks to Trolleytrainer for the proofread.