The book was hidden under the cushions of her throne.

Celestia had been reading the forbidden tome. Or rather, she'd been reading the tome which multiple organizations of deliberately-oversensitive ponies were insisting she forbid, despite all Freedom Of Expression laws to the contrary. She had made it through the first six chapters without registering a single concept as to why, along with completely failing to see where the plot was going, or if there was ever going to be one. There was a businesspony, and an intern (speaking of things she was considering banning, because the concept of 'You work for me, for free, and in exchange, I tell your potential future employers that you were stupid enough to put in triple-time without actually getting paid' arguably deserved it), and so many attempts to inflict foreshadowing and mystery into the dialogue that they acted as pounding hooves against the text, with not a single word of normal pony speech surviving the assault. That was offensive on multiple levels -- but she didn't understand why it was supposed to be a ban-worthy one. She'd seen worse, if not by much. And now, with her duties for the day concluded but for the final one, she could take the chance on seeing worse yet again, which given the way the text had basically been declining by the line, meant Chapter 7.

But she'd hidden the book after each hard-fought bout of reading. (She suspected she wasn't the only one.) Because while so many ponies (and mostly those in the Loyal Opposition, many of whom had spent weeks going through the book in order to determine exactly why they were offended -- doing so multiple times) wanted her to ban the book, those same ponies also stood ready to scream accusations of corruption and personal bias and interest if anypony ever caught her reading the thing. And it wasn't hidden all that well, not so much that a complete cleaning of the Solar throne room wouldn't uncover it -- something which was done by the Lunar staff, a process which would start relatively soon.

Still, there was nothing to worry about. All she had to do was trot down the final hallway, open the doors, and recover the book before retiring to the private library. She could even try a basic illusion spell on the cover to make it look like another book. Sadly, basic illusion spells were about all she was capable of. That category of magic was Luna's specialty. Luna could make a toy spider appear to have sprung into full, animated, horrifying life, secretly moving the plush base within a hidden field while carefully-applied magic made terrified witnesses fully believe in scuttling legs. Celestia, presented with a book to conceal, could... change the color of the cover. Somewhat. And even then, she had to be careful not to shift it too quickly, lest a patch of chroma separate from the target and be left hanging in the air...

Celestia, half-lost in memory of her own past (and depressingly, still current) ineptitude, deciding it was a chance to practice, carefully considering the exact working she would try using while simultaneously plotting a course to the library which would not intercept her sibling... almost completely missed seeing the low-lying huddle of Solar armor piled in front of the closed doors which made up the Sunrise Gate.

"HALT!"

An occupied pile.

Her legs instinctively froze. Hooves briefly skidded against white marble.

"Who goes there?" the pile demanded with as much insistence as the voice of a filly no more than six years old at best could manage: a lot.

Slowly, carefully, Celestia dropped down to all four knees, then went lower still until both belly and barrel were pressed against the marble. It still left her so much taller than the pile, with the askew helmet well below chin level.

That helmet shifted slightly. A bit of indigo snout emerged from interior shadow, along with the tiniest fraction of horn tip, which mostly served to help prop up the helmet a little more. The continuing attempt to stare up at the intruder eventually revealed unblinking grey eyes.

"Who," Celestia gently asked, smiling, "wants to know?"

The pile thought about it.

"Nexima," it eventually said.

Celestia's practiced memory sorted through endless files of names.

"Oh... you're Cluster's daughter!" The younger of the two. "What are you doing here, little one?"

The filly shifted a little within the pile, which now appeared to be the results of a very sincere attempt to wear armor approximately twenty sizes larger than the current borrower.

"My First Daddy is a Guard," she declared.

"Yes," Celestia agreed. "A Lunar one." Still smiling.

"So... I'm a Guard."

Celestia considered the evidence.

"Why are you wearing Solar armor?"

This answer came immediately. "'cause it's day!" The helmet briefly turned towards the nearest window. "For a little while." Resumed its endless scrutiny of Celestia, where it had quite a bit left to go over.

Of course. Back to the original question. "What are you doing in the palace today?"

"Guarding!"

Maybe another approach. "Did your father bring you?"

The helmet nodded, nearly falling off the horn. "Second Daddy has a concerto... a considerable... a content... a conference! He couldn't pick me up from kindergarten today. So First Daddy brought me to the palace. He came in early."

"So... where is he now?"

"Doing Guard stuff." A pause. "Early."

"And... where are you supposed to be?"

"Here!" More thought. "'cause I'm a Guard."

The smile was starting to feel a little forced. All right. Somepony probably saw Cluster arriving ahead of shift, decided they'd use the time, or at least the stallion, and called him away. He left her with somepony else, she escaped that supervision... but this is as far as she got. After getting into the armory and I'm going to need to figure out how she managed that, but the security spells around the weapons are clearly holding and nopony's hurt. I just have to find Cluster and get him to herd his daughter again.

After I get the book.

"Well, it was very nice to meet you," Celestia told the filly, and started to stand up again.

"HALT!"

She sank back down.

"Who goes there?" demanded the most underaged Guard never to have been hired.

The word Really? went through Celestia's mind, picking up several friends along the way.

"Princess Celestia," she eventually said.

"Prove it."

This stare was coming back in the other direction.

Wings flared, just a little, at the same moment a touch of brilliant yellow corona ignited around the horn. "And why --" just the slightest emphasis on the word "-- do I need to do that?"

"'cause I'm a Guard!" declared the pile. "And you could be an assassassassin. Or a spy. A sneak. A thief. A faker! And nopony should go into Princess Celestia's throne room unless they're Princess Celestia! Or... a Guard. Or they're invited. Or an ambassassador. Or..." The list went on for a while, but eventually wrapped up with "...a cleaner!"

She flared her wings a little more, added an extra lumen to the glow. "Little one --"

"Guard!"

"-- I have wings and horn both. My mane is shifting as we speak. Who else could I be?"

"An assassassassin! Or a spy! A sneak! A --"

"I'm not." An oddly quiet protest, as such things went.

"Prove it! And wink your field out! If you use magic on a Guard, that's assassault! And a true Princess doesn't hurt ponies!"

She had so many ways of getting past this tiny obstruction, and all of them gentle...

But she smiled.

"All right," Celestia said, and her horn went dark as her wings settled back into the rest position. How hard can it be to convince a kindergartener? "How do you want me to do that?"

The filly appeared to be concentrating deeply. Or at least, the shifting of shadows within the helmet suggested some level of intense thinking was under way.

"Tell me something only the Princess would know. Her and nopony else in the whole wide world."

"All right," Celestia agreed, wondering what she was about to be asked. The number of stars in the sky, possibly. "What do you want to know?"

And in total, innocent sincerity, "What's the Princess' mommy's name?"

Celestia blinked.

Foal questions. There was a reason they were called that. Queries so basic, so simple, so innocent that only the youngest would ask them at all...

When was the last time I said it aloud?

When was the last time I said it at all?

Years. So many years since I told...

It took a moment before she realized her feathers were vibrating. That there was a tiny bit of sweat forming in her coat. The near-endless shifting of her mane had completely stopped. And then there was a little more time to gather strength, to force her attention to the now as she prepared herself.

No harm. No harm possible. It'll just be a story she made up. Nopony will...

And found that more than anything else, she just wanted to say it.

The vocalization of words she had said, on average, less than once in a pony's lifetime.

Her forehooves were trembling.

"My mother's name," Celestia softly whispered, "was --"

"-- HAH!" the filly crowed. "You're not the Princess! So you can just go away, right now!"

Another blink.

"...I'm not?"

Triumph. "It was a tricky question!"

"...it was?"

In declaration of absolute victory, "Everypony knows Princess Celestia doesn't have a mommy!"

Celestia found her right forehoof resting against her forehead, and wasn't entirely certain how it had gotten there. (The surge of internal sorrow, however, had a very clear origin.)

"Little one," she carefully tried, "if I don't have a mother... then how do you think I came to be?"

"Everypony knows that!"

She lowered the hoof. "Pretend I don't."

The filly thought some more.

"'cause you're a spy from somewhere which doesn't teach ponies stuff," she decided. "So you don't know. And it's not a secret, 'cause it's learned in school. I guess that makes it safe to tell you." Suspiciously, "Unless I hear you telling somepony else..."

"That," Celestia gravely said, "will not be happening."

The pile gradually settled into a lecturing pose.

"You know the Sun?"

"A little," Celestia admitted.

"It's an egg."

"Really."

The helmet nodded. "And one day, it cracked open. And there was a golden yolk inside. And the yolk poured out into the air, and Sun baked it. The gold became her magic, and the egg white turned into her body. That frothy fringe on the edge of a fried egg is her wings. And that was Princess Celestia. She's an egg yolk. Shaped like a pony. But she's all egg inside."

Celestia took a moment for listening to her own breath, feeling her heart beating, and noting the complete lack of chalazae anywhere.

"Little one," she gently asked, "who told you that?"

"Alizia."

"And who's that?"

"She's my best friend," the pile proudly said. "Who's a griffon. I have a griffon for a best friend! And she knows everything. 'cause she's in first-year for her school! And in first-year, they teach you everything." Pause. "I can't wait to get to first-year so I can know everything too!"

Celestia made a mental note to review the Protoceran elementary educational curriculum, and soon.

"Well," the helmet added after some thought, "I guess she really knows everything minus two weeks. 'cause there's still two weeks of school left. So she knows everything except what they teach you then. But it can't be very important or they wouldn't have made it wait so long."

"So somepony taught her this in school," Celestia not-quite-asked.

"Where else would she learn everything?"

In this case, possibly from listening to the echoes in her own head. Or just from desire to prove that she's the dominant one in your friendship, because she can make you believe anything. "So I hatched from Sun. Which is an egg."

"No," the helmet suspiciously said. "You didn't. The Princess did,"

"So why is Sun still in the sky, if it broke open?"

"It's a magic egg," the pile said with the patience of a filly explaining something to a foal who had no chance of getting accepted into the most remedial kindergarten.

"And..." She was almost dreading this part. "...where did Princess Luna come from?" Awaiting the news that Moon was secretly a clamshell.

"Some of the yolk got burnt."

Celestia stopped breathing.

"That's why she's so touchy all the time," the pile told her. "'cause she knows she's overcooked. And nopony likes the yucky burnt stuff!"

Celestia's inner vision ran a few quick scenarios of her sister's reaction to learning that she was the unplanned result from a random act of cosmically poor cooking, judged them against the generally-(in)accurate Luna's Temper Meter, and came up with one staredown, three bursts of thunder, four all-out assaults on the griffon educational system, a single extensive personal lecture delivered to Alizia, and the not-as-remote-as-it-should-be possibility of a very quick major war.

"I don't think," she finally managed, "anypony should tell her that."

"But she already knows --"

"-- ever."

It was the filly's turn to blink.

"...okay."

Silence briefly held reign over the hallway, at least once the final echoes of 'ever' died away.

"Is there any other way," Celestia patiently asked, "in which I could prove myself?"

"But you didn't know the Princess doesn't have a mommy!"

"I was rather close to Sun when the cooking happened," Celestia gravely stated while considering all the many ways she might wind up paying for this one later. "I may have gotten a touch of heatstroke."

The filly frowned.

"Are you sure you're not a changeling?"

She held back the groan. "I'm not."

Suspicious peering.

"I should check that," the filly decided. "'cause I'm a Guard. And Guards check for changelings. Like my First Daddy does."

"And how," Celestia asked, "do you plan on doing that?"

The helmet slowly shifted, up and down.

"A bucket. With water in it."

Celestia was slightly impressed.

The water trick was the most reliable quick test known and had the benefit of being something everypony could do. Following the post-invasion mop-up, hasty studies of changeling shapechanging had taken place. To find out how to spot it -- and how changelings could effortlessly manage a feat which had sent generation after generation of magical researchers into hospitals for treatment of bones which had just fractured themselves. And what they'd learned was that no physical shift ever took place. Changelings made their targets think they looked like somepony else.

It seemed to be a universal ability -- but the strength was a variable. The weakest changelings... they could only fool one sense, and generally chose to make that vision, staying silent within the disguise at all times. To rub flanks against one of the lowest-ranked would produce the sensation of fur and flesh contacting chitin. The strongest would fool even touch, and the tricked pony mind would conjure warmth coming back. Even those on Chrysalis' level seemed to need periods of rest, allowing the disguise to lapse while they recovered their strength -- but someone like her could fool every sense, visual through thermal, and keep it up for hours.

But that magic did nothing to fool the environment, for that which lacked a mind could not be tricked. Edged chitin contacting softer material would scratch: clumsy changelings tended to mark their surroundings and avoided physical contact with ponies, lest supposed skin wound those it touched. And even with the most careful... a precise gout of water aimed at the legs would have some of the fluid pass through the holes in the lower section of those limbs, producing a distinctive splash pattern on the other side. Ultimately, all it took to reveal most changelings, at least until the hive finally caught on and started to armor their legs, was a bucket of water. And once that had been discovered, Equestria had spent one full post-invasion day in a collective drying-off of true citizens, with the false restrained and dragged away from freshly polka-dotted streets.

Of course the younger daughter of a Guard would remember the bucket trick. And really, the filly was trying so hard...

Celestia checked her internal clock, noted how much time was left until Sun-lowering. I can indulge her a little longer.

Besides, if I say no, she'll probably find one of the more panic-prone Guards and start screaming about changelings in the palace.

"All right," Celestia agreed. "The bucket test. Let's go find some water." She stared to stand up.

"HALT!"

And stopped.

"No..." the pile suspiciously decided. "You stay right here. If you are a changeling, you can't see more of the palace. The palace has secrets. Stuff First Daddy won't say 'cause it's so secret and not 'cause there isn't anything to tell like he keeps saying. I'll get the bucket. All by myself. Guards can do that." The helmet turned just enough so that the occupant could theoretically regard the doors into the throne room. "And you have to promise to stay here. And not trot inside. Only a changeling would go inside when a Guard didn't let her in. A true Princess wouldn't."

Celestia held back the sigh. "All right." But that left --

"-- and you can't fly in. Or teleport. Use -- other magic. Any kind of magic at all. You can't do anything but promise to wait. Like a true Princess."

Celestia silently considered how much she suddenly wanted to meet a true Princess in battle for what promised to be the shortest fight in recorded history before finally nodding. "May I stand up?"

"Why?"

Steadily, "So you can splash my legs when you get back."

"...okay. But that's all."

"Fine."

The pile, after considerable effort, raised a quarter hoof-height off the floor and began a very slow shuffle past Celestia's legs, little pieces of armor falling off along the way.

Celestia watched it go. There was plenty of time in which to do so.

She settled in to wait.

She kept waiting.

The internal clock was checked again. Several times.

I could just teleport in, get the book, drop it off somewhere, come back here...

No.

All right, Celestia argued with herself, I know I'm being too indulgent. But...

She was also frequently too lenient with children, and she knew it. But she'd never had much of a childhood herself, certainly not by modern standards, and so was reluctant to bring unwelcome reality into Nexima's waking dream.

Let her be a Guard for a day. It did no harm.

Besides, she would hear if anypony entered the throne room from the other Gate. The cleaning staff would never get a chance.

More time passed, seeming rather satisfied with itself...

...there seemed to be an irregular scraping sound coming from the far end of the hall, much like an exceptionally-clumsy changeling repeatedly skidding across marble. Celestia turned and waited for the source to come into view. Eventually, it did.

The filly had not found a bucket. She had found a wooden hoofbath. One of Celestia's own discarded ones, a iron-banded certified antique which hadn't done service in twenty generations. And somehow, without being spotted, much less stopped, by a single Guard (or perhaps having just indulged her way past them), she'd gotten the ancient oak tub out of wherever it had been stored (and Celestia had no idea where that had been), partially filled with water and all the way to this point through what had probably been most of the Solar wing...

There were three problems with this particular approach.

The first was that the filly had no magic. Her infant Surges were a thing of never-quite-recaptured memory, her first sparks years away. And so she had the only resort any unicorn filly of her age possessed when it came to moving things: to push with her own body.

Second: Nexima was rather on the small side, even for a kindergartener.

Third: the hoofbath was one of Celestia's, which meant it could readily serve as something approaching a bathtub for just about anypony else and, with the filly, was virtually a not-very-portable swimming pool, one which was almost as tall as the little body. And that waiting volume was only partially filled with water -- but water had weight. The pretend Guard could only move the thing by shoving her entire body against it and most of the time, the contents shoved right back. Nexima was sweating heavily, and Celestia was amazed it hadn't transitioned into the danger of froth.

On the bright side, most of the armor had fallen off along the way, which meant that much less extra weight was being carried. What few pieces remained (including the precariously-balanced and now slightly-dented Solar helmet) served to shield the filly's body on each pushing impact.

Celestia's horn instantly, sympathetically ignited. It would be no effort at all for her to bring the hoofbath the rest of the way --

"-- HALT!"

"But --"

"No magic! Not on the bucket! You could make the water splash wrong!"

"I know a spell to cut down friction on the floor..."

"That's magic!"

"Yes..."

"Don't do it!"

"Can I just push it for you --"

"I'm a Guard!"

Celestia sighed. And then cheated.

It was easy enough to hide her field, especially from a filly too young to truly feel. And so she invisibly tugged every time the little body went for the wood, making it move five times the normal length for each effort. Then, when that still threatened to push things into Sun-lowering (which was now very close), eight.

"...see?" the filly finally panted at the end of the sweat-covered trail, with the hoofbath now a standard body length away from Celestia's waiting forelegs. "I did it! Guards do this stuff all the time!"

She looked up at Celestia. The helmet nearly fell off.

"So now," the filly declared. "I just have to splash you."

She looked at the hoofbath.

After a moment, the little body reared up, planted forehooves on the edge, and heaved until narrow belly was against wood. The helmet nearly fell off again as her front half tilted over the pivot point, reaching for the water...

The left forehoof, which could just barely reach the liquid, flicked at the surface.

Two tiny droplets impacted Celestia's right foreleg. Three other, smaller ones, had lost cohesion during the exhaustive journey and surrendered spent bodies to the air.

The helmet tilted up.

"Um..."

Celestia, who now knew better than to offer open help, waited.

"I can do this."

Celestia nodded.

"How," the filly said to herself, "would Alizia do it?"

Well, at least she didn't ask about a true princess...

The filly's coat seemed to lighten. She heaved herself out of the tub, got all four hooves back on the marble, leaving a faint film of water on the surface, which lightly diluted the fallen sweat.

"Don't move! That's a Guard order! I'll be right back!"

"I --"

And before she could say won't, Nexima was at full gallop, racing down the hall, around the bend --

-- out of sight.

Maybe she's decided to call for backup. That seemed like the best case. She'll bring in another Guard, whom she'll clearly trust more than she trusts me, and the other Guard will -- and why am I thinking other Guard? And the one Guard will do the test for her, explain everything, and I can finally get the --

She heard little hooves pounding against marble, very quickly. Only four of them.

She found one of the pegasi?

And then a single tiny body came around the bend at that same full gallop, with that barely-visible horn tip lowered.

It took less than a heartbeat for Celestia to realize what was going on. The filly was going to charge the hoofbath. Trust that the force would be enough to make the water splash. And it wouldn't work, the physics were still all wrong, too much resistance on the receiving end, and those last pieces of armor were falling away --

-- the helmet went.

And it went at the exact moment Nexima slipped in her own fallen sweat.

The little body helplessly skidded down the floor, too scared to even scream an alarm of helpless panic. She was going to hit the hoofbath, not with unbreakable horn, but with spiraling legs or ribs or head. And Celestia saw the terrified wide eyes, her field ignited and lanced forward, but she'd promised not to use magic on the filly --

-- the glow of sunlight surrounded the hoofbath. Yanked.

There was a moment of impact. Or in this case, two.

Silence. Except for the dripping.

Slowly, Celestia's field lowered the wooden tub to the soaked marble floor.

"Are you all right?" she asked the filly, who had her tail against Celestia's left hind leg.

"...yes."

"You're sure?"

"...yes."

"Come out here where I can see you."

The filly got up, slowly trotted out from under Celestia's shadow.

"I'm okay," she said, and she looked it.

"You could have hurt yourself."

"But I --"

"You could have."

More drips.

"...I'm sorry."

"You have to be more careful."

There was a little defiance left. "Guards take chances!"

"Guards," Celestia said, "want to kiss their daughters when they come home in the morning, and untuck their sheets so they can get up for school. Bedsheets. Not hospital sheets. And so they don't take chances which would keep that from happening. Not unless somepony's life is at risk."

"But..."

"Does your father kiss you when he comes home in the morning?"

A tiny nod.

"Do you want him kissing hospital bandages instead?"

And now there was a new source of drips.

Celestia sighed, levitated a wall hanging, used it to wipe weeping eyes and runny nose. "I'm sorry, little one. I didn't mean to scare you, but..."

Softly, through the golden edge weave, "I'm not a real Guard. Real Guards aren't stupid."

For the final time that day (and in part because there was so little day left), Celestia sank down to the soaked floor. Her right foreleg hooked out, curled the unresisting filly in close. "You could be a real Guard one day."

Sniffling. "I... could?"

"You're dedicated enough," Celestia smiled. "But... it has to wait until you're older."

Bright grey eyes gazed up at her.

"After first-year?"

"Longer."

"But that's when I'll know everything!"

"Little one... if you learn everything in first-year, then what are all the other years for?"

The filly thought about it.

"To learn... more than everything?"

"For starters," Celestia said.

After a while, Nexima got to her hooves and moved a few body lengths away. Turned back to look at Celestia.

"Can I see your legs?"

Celestia silently stood up.

"The splash is all wrong," Nexima decided.

It was. Celestia had pulled the near-tub towards herself -- open top first. The hoofbath had gotten out of the way in a hurry and, thanks to the resulting momentum, so had the water. Her entire body, from snout to the base of her semi-tangible tail, was soaked, and so was the floor around her.

"So I didn't prove I'm not a changeling," Celestia sighed. "Would it be all right if I just found somepony who could vouch for --"

"You're the Princess."

Celestia stared at her.

"I was gonna get hurt," Nexima said. "A thief or a spy or an assassassassin would have let me get hurt and then gone inside. A changeling would have just laughed. You saved me. Like a true princess." And before Celestia could react to that, those bright eyes met her own. "You... really had a mommy?"

Celestia's eyes closed.

"Yes."

"What's her name?"

And then, counting the siblings, there were four ponies alive who knew.

"It's a pretty name," Nexima whispered.

'Yes," Celestia smiled, and opened her eyes again. "So... I just have to pick up something inside, and --"

"HALT!"

All four legs froze.

"I proved I'm myself. Right?"

"Yes."

"So -- why am I halting?"

"Because my First Daddy says... redundudundant security measures are important. To keep things from going wrong."

Celestia, with surprising dread, waited for it.

"So... we did the Sunrise Gate tests." And with the rising enthusiasm of a True Guard in the making, "So all we've gotta do is go to the Sunset Gate and start the whole thing over! And any true Princess would understand that! 'cause she'd want to make things safe! Like you just did!"

Slowly, Celestia turned. Her posture assumed a bearing of absolute regal calm. And, dripping said regal calm all over the floor, she trotted past the filly, down the hallway, around the bend, and out of sight.

Nexima watched her go. Then she glanced up at the nearest window, just in time to see the last rays of Sun pass through.

"Oh!" she happily said. "Shift change!"

And with that, she too trotted away, leaving the mess to the Lunars.

A few minutes passed. And if anypony had been listening at the door, they might have picked up on the very quick, almost desperate sound of a teleport arrival, followed by cushions being field-flung across the room, and concluded with an even hastier teleport exit. But nopony was.

Celestia had been curled up on her personal reading couch for about an hour when Luna entered the room, with a familiar-looking book silently floating within the dark field.

"Good evening," the younger carefully said.

"Hello, Luna."

"Some reading before you take to your bed?"

"Yes."

"I thought I would do the same before the Night Court session began."

"Of course."

"In discretion. And relative privacy. With no thoughts of anything which is not the book."

"Naturally."

Luna silently curled up on her own couch. A flicker of dark field opened her copy.

"Do you think they will ever manage to actually do something?"

"What chapter are you on?"

"The tenth."

"They still haven't gotten around to a plot?"

"There has been some discussion of a contract. Perhaps this is a new trend in relationships. One I hope to miss. Forever."

Celestia sighed.

"I can't say I'm looking forward to getting that far."

"Yes," Luna dryly said. "Sometimes, reaching a destination is truly more trouble than it is worth..."

And they sat and read together as Celestia carefully ignored the water stain steadily soaking into Luna's cushions.