Author's Note

Lyra and Bon Bon had votes from previous rounds, and with one more half vote due to them being mentioned again in the last round of voting, they won out.

Scootabom1 once again was the first to propose what to do with them, suggesting that Lyra allow herself to be mentally regressed, as well as Twilight building a pillow fort with Bon Bon, and Lyra getting finger gloves as a reward. And Tiber Septim II proposed the idea of Lyra and Bon Bon both telling Twilight a sad story, which would make them and her cry, and Princess Celestia would comfort them.

I did also draw on inspiration from Lyra's prompt from "Potty Training Tales", which itself built off the Monndancer prompt (Lyra's prompt can be found here for those interested). And the name of Bon Bon's secret organization comes from the chapter book "Lyra and Bon Bon and the Mares from S.M.I.L.E.".

As always, you can vote for any characters who are not ineligiable due to the rules and restrictions. If a character has already been done before, you can vote for them again but only if they're appearing with at least one other character. And if this fic continues long enough for repeats to appear, characters who appear a second time will be permanently ineligable unless otherwise noted.

On the subject of Equestria Girls characters, as of right now only Sunset Shimmer and the Dazzlings will be allowed, again due to the nature of this fic and the fact that many of the human counterparts to ponies would be considered minors, and I don't want to risk any issues of potentially using characters under the legal age of consent.

Characters ineligable under any circumstances:
Starlight Glimmer
Discord
Trixie
Sunburst
Cutie Mark Crusaders
Flurry Heart
School aged or younger children (i.e. Cake Twins)
Characters introduced after Flurry Heart (Starswirl the Bearded, the Pillars, Star Tracker, Mudbriar, etc.)
Equestria Girls characters other than Sunset Shimmer/the Dazzlings

Characters that can only be done in group pairings:
Mane six
Spike
Princess Cadence
Shining Armor
Princess Luna
Octavia and Vinyl Scratch
Twilight Velvet
Spitfire (with or without Wonderbolts)
Lightning Dust
Maud Pie (without Mudbriar)
Moondancer
Cheerilee
Lyra and Bon Bon (separately, or together)

Characters previously voted on:
Coco Pommel - One vote
Spike and Shining Armor (Together) - One vote
Limestone Pie, Marble Pie, Sassy Saddles, Fleur - One half vote

Little Lyra and Special Agent Sweetie Drops (Lyra and Bon Bon)

Princess Celestia didn't know whether to laugh or to groan at Twilight's antics this time. She had decided to give the padded alicorn a bath. Just a regular bath, mind you, not a bubble bath.

But Twilight apparently didn't think she needed a bath, and had tried to run away. It was of course futile, she was quite easily pulled towards the bathroom and the bathtub by the sun princess. But she was still squirming and rebelling. "I don't wanna take a bath, Mommy!"

"But Twily, don't you want to get all nice and squeaky clean?" The sun princess cooed. "You haven't had a bath for days now. Just imagine how filthy you must be. You're starting to smell worse than one of your dirty diapers. And that's saying something."

Twilight frowned. "I'm not that stinky, Mommy." Despite her protests, her diaper was removed and she was plopped into the tub with an audible splash.

Celestia, undeterred, just set to work scrubbing her fellow alicorn until she was clean and smelling nice again. Then, after pulling the plug and letting all the water in the tub drain out, she lifted Twilight out and placed her onto some towels, then used her magic to dry the alicorn before putting her diaper back on. The whole process had taken only a few minutes at most. "There we are. Now was that worth making such a fuss, Twily? I don't think so."

The padded alicorn sighed, waddling out of the bathroom and grabbing Smarty Pants. "Hey, Smarty Pants. Thanks for waiting for me while Mommy made me take a bath. It wasn't even a bubble bath."

"Oh, but Twily, you used to love bath time," Smarty Pants cooed in encouragement. "It was your favorite time of day. Besides potty time, of course. That was the only time you could read as much as you want without anypony ever asking you to do anything else."

Twilight nodded and nuzzled the stuffed donkey. "And you were always by my side no matter what, Smarty Pants. Now that I think about it, you were the first friend I ever had," She then cooed. "I think everypony should have a friend like you once in their lives. Maybe I should pass a decree or something."

Smarty Pants giggled. "While you're still in diapers, Twily? What would everypony think? They'd start calling you the princess of pampers."

At that the padded alicorn blushed bright red with embarrassment. "S-so, even princesses wear padding sometimes."

Princess Celestia chuckled. "Well, you know what all the papers would say if they found out about your secret," She gave a knowing wink. "I've had my fair share of embarrassing press stories over the years," Then she coughed into a hoof and changed the subject. "But we can discuss that some other time, Twily. For now, you're not just a princess, you're my little princess. And because my little princess has been so good lately, I think it's time for her reward."

Twilight's ears perked up, realizing what her fellow alicorn meant. "So who's my playmate this time, Mommy? Is it somepony I already know, or is it a total stranger?"

The alicorn mare with a majestic white coat replied by lighting up her horn while looking back to the bedroom door. "It's both, actually. And they should be here right about... now!" After she'd finished speaking, the door opened up, and out tumbled two ponies in diapers as thick and as large as the ones Twilight always wore. One of them was a unicorn mare with a sea green coat, and the other was an earth pony mare with a cream colored coat. Strangely enough, both appeared to be wearing black stealth suits and sunglasses.

The earth pony mare stood up, grumbling. "Looks like our mission is a bust, Lyra. We've been captured."

"Lyra", for her part, just giggled as she poked at her diaper. "Hehe, poofy!" It was even possible to see a little bit of drool escape her lips and dribble down her chin.

Twilight's eyes went wide! For the first time since Vinyl Scratch and Octavia, she had two playmates! And unlike them, she recognized one of the ponies. The unicorn was none other than Lyra Heartstrings, one of Twilight's old Canterlot friends, and one who had subsequently moved to Ponyville (years before Twilight did the same). She turned to Princess Celestia, hugging the older alicorn as she exclaimed! "Thank you so much, Mommy! Two playmates means twice as much fun!"

The cream colored earth pony mare seemed to grumble a bit as she turned to the sun princess. "So that's it! This was all a set up! I knew something was up when you asked us to 'volunteer' for an 'assignment'. I thought we were just supposed to sneak into the castle, and the diapers were just so we wouldn't have to take bathroom breaks," She then remarked. "Is this because of that bugbear incident all those years ago? I thought we'd moved past that when you reinstated S.M.I.L.E."

Twilight blinked in surprise. "'S.M.I.L.E.'? She had never heard of such a term before."

The earth pony mare removed her sunglasses, quickly scanning the room. After she was certain the coast was clear, she waddled towards the padded princess and explained. "It stands for: Secret Monster Intelligence League of Equestria. And our existence is supposed to be top secret. It was so secret, I had even to operate under the name of Bon Bon, rather than Sweetie Drops," She somewhat sheepishly confessed. "But I kind of like Bon Bon better. It's because of that name and the persona I adopted that I was able to meet my best friend and special somepony: Lyra Heartstrings."

Lyra smiled and waved a hoof. "Hi." She spoke in a noticeably foalish sounding tone of voice.

Twilight looked at Lyra, noticing the far away glance reflected in the unicorn's eyes. She then turned to Bon Bon and hesitantly asked her. "Is Lyra okay? She seems kind of out of it."

Bon Bon sighed as she looked to Princess Celestia. "Lyra's fine. She specifically asked Princess Celestia to turn her mindset into that of a foal. When Princess Celestia approached us in secret, she said she had a special job for us, a top secret one at that. But all she told us was that we had to put on diapers and infiltrate the castle. And once diapers came into it, Lyra made the request to be mentally regressed. She has the mindset of a two year old, maybe a three year old."

Smarty Pants giggled. "Lyra is so silly!"

Bon Bon blushed. "Honestly, I hope she doesn't remember anything about this. This is so embarrassing and humiliating. Not only did we get caught by the same princess who wanted us to sneak into her castle, but now I'm starting to see what the real reason was," Then she turned to Smarty Pants. "By the way, I seem to remember that the last time I saw you, Twilight had enchanted you to make everypony fight over you."

Twilight looked down at the ground in shame and whimpered, trying to hide behind Smarty Pants as the doll explained. "Well, Twily didn't mean for things to get that out of control. As for me, Big Macintosh apparently loved me even without the spell. He took me home, and I had to spend the next year and a half with him. Usually, that meant being Winona's favorite chew toy. It was very lucky for me that Big Mac knew how to fix me up every time. Never knew he was so skilled with a needle. Then, when Twily became an alicorn, Big Mac dropped by and gave me back to her, even apologized and said he never meant to hold onto me for so long."

The earth pony mare just replied in a low sounding tone of voice. "Well, if you or Twilight ever do anything like that to me again, I'll make you regret it. I was S.M.I.L.E.'s top agent for a reason, I learned a lot of things that I could put to very good use if given the right incentive."

The alicorn princess eeped. "P-please, don't hurt me! I'm so sorry!"

Bon Bon giggled, flashing a knowing wink. "Relax, I was only kidding. At S.M.I.L.E., we only dealt with reconnaissance and capture. We operated entirely in the background, often going deep undercover. And lucky for me," She turned to Lyra with a smile. "They were willing to make an exception to let me stay with Lyra and bring her into the agency when it was re-established. The alternative would've been to erase all of Lyra's memories of me. And I'd sooner die than let that happen! Lyra is the pony who found a way to pierce my defenses, bring out the best in me. That's why we're officially a couple now," A slight chuckle escaped her lips. "Even if she's currently back in diapers."

Twilight giggled. "Well duh! Mommy wanted you two to be my new playmates. And this time she wanted it to be a surprise."

Princess Celestia replied in an innocent sounding tone of voice. "Come now, Twily. You make it sound like it was a devious ploy on my part. It really wasn't. Besides, even I don't know why Lyra chose to have me mentally regress her. I know she was one of your classmates when you were attending my school, but that's the most I know about her. If anything, I would've thought Bon Bon would be the one asking me to regress her, she once told me that she's been in S.M.I.L.E. her whole life. And her parents were too, apparently."

Bon Bon nodded. "It's true. And apparently, my parents aren't the only S.M.I.L.E. agents who had kids. I can't name names, you understand, but let's just say that I don't think they fully realized how much of an 'adventure' it would be to have and raise a foal. From what I've seen though, the kid's doing pretty well for herself. Her parents are at least smart enough to have trusted ponies keeping an eye on her whenever they're out of town."

Lyra, meanwhile, was just giggling as she plopped onto her padded rump and poked at it some more. She began sitting in that pose she was so famous for sitting in: Upright, with her front hooves folded to either side and her back hooves spread out in equal measure. She seemed to be enjoying herself, not having a care in the world.

Celestia then commented. "Well Special Agent Sweetie Drops..."

"Please just call me Bon Bon. I'd prefer not to mix my S.M.I.L.E. work with this." Bon Bon insisted.

"Oh, but you could easily spin this as undercover work," The sun princess said with a knowing wink. "Think of it as getting into character, just like all that background work you were so good at."

The earth pony secret agent just shrugged, fully removing her sunglasses and wiggling out of her black stealth suit. Then she helped Lyra do the same, the unicorn mare not putting up a fight as Bon Bon did so. It seemed that even with her mind regressed, a part of her still had that connection and that trust with her special somepony.

Once both Bon Bon and Lyra had more or less changed out of their secret agent attire and had stripped down to just wearing their thick diapers, they waddled over to Twilight and Smarty Pants. Bon Bon then asked the padded princess. "So, what do you wanna do, Twily? That's what I'm supposed to call you now, right?"

Twilight nodded. "Uh-huh. I'm Twily, and Princess Celestia is my mommy."

"Mommy!" Lyra cooed as she gazed at Celestia.

Princess Celestia was quick with the reply. "You can call me mommy if you wish. Do whatever makes you feel comfortable. All I ask is that you're nice to Twily and to Smarty Pants."

Smarty Pants replied. "Yeah, don't play too roughly with me or anything. I can take a lot, but I'm not invincible. And if you want to do something with me, you have to ask Twily first because she and I are inseparable. We've been together since she was in diapers."

"But isn't she still in diapers now?" Bon Bon questioned with a quirked brow.

Twilight gave a foalish giggle, clapping her hooves together as she was all too happy to explain. "Duh, she meant when I was in diapers the first time, when I was an actual foal instead of a big foal. Smarty Pants was a present from my parents on my first birthday. And she's never left my side since! Well, aside from that one time, but you know what I meant!" She hugged the doll tightly! "Smarty Pants gave me the confidence to take on the world I never could've found otherwise. She was always there for me no matter what: Whether I was a good little pony or not. And she never complained that I was too noisy, or too stinky, or anything like that."

Bon Bon nodded and smiled. "I see. You two are a lot closer than I would've imagined from that little 'incident' in Ponyville. Then again, I'm not a unicorn like you were or like Lyra is, so who knows if I would've ever thought of enchanting one of my old dolls."

Lyra pointed a hoof to her forehead as she stood up. "Magic," She loudly proclaimed, only to lose her balance and fall down. She landed right on her padded posture and proclaimed. "Oopsie! Go boom boom!"

The earth pony mare let out a sigh of regret upon watching the display. "Look at her. She doesn't have a care in the world. And she makes it all look so easy," She turned to herself. "I'm still trying to get used to moving around in these diapers. I know they're meant for big foals like Lyra and I, but do they have to be nearly this big?" She demonstrated this fact by spreading her legs apart as best she could, revealing just how much more space the padding seemed to create.

Lyra giggled again as she stood up, waddling over and nuzzling Bon Bon. "Bon Bon nice."

"You always say that, Lyra," Bon Bon sweetly replied and nuzzled her special somepony. "But I wouldn't have it any other way."

Smarty Pants, meanwhile, was questioning something she seemed to have noticed about Lyra. "Hey, Lyra," She called to the unicorn. "I know your mind's been altered, but how come you're not talking so much compared to Bon Bon? When Twily was two years old, she was quite a chatty foal. She loved to talk about anything, especially if she read something interesting."

Twilight puffed out her chest. "Uh-huh. I was even able to read grown-up books, that's how smart I was. Though I... did need a little help making out some of the bigger words," Turning to Lyra, she said to the unicorn. "Still, I do seem to remember that you could talk just fine when you were two years old. Moondancer and I were well aware of that, especially once we found out you were actually slightly older than us. In fact, I think you were the oldest out of everypony in our group," She blushed. "I think I was the youngest, just barely."

Lyra was silent for a moment, maybe two. She seemed to be deep in thought (which must've been hard given her mentally regressed state). Then she opened her mouth, seemingly ready to explain herself. Before that could happen, however, she suddenly seemed to recognize some kind of urge inside of herself. She raced off towards the bathroom while shouting! "Potty!"

"Lyra, wait!" Bon Bon frantically called out to the regressed unicorn!

Lyra, however, refused to wait! "Gotta go! Gotta go! Gotta go!" She said over and over again, hopping back and forth from one back hoof to another as she made her way into the bathroom and approached the toilet. Somehow, the unicorn mare was able to lift up the lid of the toilet, pull down her diaper, and scramble onto the toilet seat. Within seconds of doing so, it was possible for everypony to hear a steady tinkling sound echoing into the toilet bowl below.

Twilight was utterly speechless at the display! It shouldn't have been possible for Lyra to do all of that all by herself while mentally regressed. But apparently, some instincts couldn't be suppressed by magic. And apparently for Lyra, her potty training was one of them.

Soon, the mentally regressed unicorn mare was finished. She graciously grabbed a few toilet paper rolls to wipe herself clean, then flushed the toilet and jumped down. Using her magic, she pulled her diaper back up and then waddled to the sink to wash her hooves.

The padded alicorn felt something stir up deep inside of her. Something she thought had been taken out of her long ago as a result of what had happened at her third birthday party. But somehow, some way, it had come back. She wasn't about to be outdone by one of her peers, mentally regressed or not. She was determined to prove she was just as capable of being a big pony. So she trotted past Lyra and made her way to the toilet, determined to try her luck with the almighty porcelain throne.

"Twily?" Princess Celestia called as she witnessed the odd behavior from the padded alicorn.

"Not now, Mommy, I'm going potty!" Twilight huffed as she climbed onto the toilet seat and sat down, swishing her tail in the process. Then she sat there, and sat, and sat, and sat some more. Minutes seemed to tick by with nothing happening. But at last, the padded princess sighed as her bladder finally began to empty itself. Except, something was wrong. There was no sound of anything tinkling or hissing, nothing seemed to be echoing into the toilet bowl. A horrifying realization struck the padded alicorn as she looked down at herself, only to realize too late that she had forgotten all about taking off her diaper!

So it was that Twilight ended up peeing into her diaper instead of the toilet, much to her embarrassment and shame. She couldn't stop herself from sniffling as she sat there, even long after her bladder had emptied itself fully.

Princess Celestia trotted into the bathroom a short time later, quickly reaching out a hoof to comfort her fellow alicorn. "Twily, it's okay. Accidents happen."

"But... but... but I wanted to be a big pony, like Lyra." Twilight sniffled and softly sobbed as she sat there in her soggy diaper.

The sun princess gently reassured Twilight as she lifted her off the toilet and put the lid down. "And you still can be. There's always next time. One accident doesn't mean you're not ready for the potty any more than one successful trip to the potty means you're ready to get out of diapers, regardless of whether it's a number one or a number two thing," She carried the padded princess out of the bathroom, and used her magic to gently float Twilight onto the changing table. "Now just relax. We'll get you changed into a fresh diaper in no time. Then you'll feel much better."

And indeed, Princess Celestia was right. When Twilight's rump was wiped and powdered, and then strapped up into a new diaper, her overall mood seemed to improve. Now her little mishap didn't seem like such a big deal after all. Not with her mommy there to comfort her and reassure her that everything was okay.

Lyra immediately waddled over to Twilight when she was set back down again. And the unicorn mare with a sea green coat apologized sincerely. "Sorry you had your accident, Twily. I no mean to make you feel bad. I just not want to use my diaper, that's all."

Twilight hugged the padded unicorn. "I should've known about that. Even when Moondancer and I were swept up in that silly competition of ours about who was more of a big girl, you never cared. You even still wore diapers until Moondancer and I both graduated to pull-ups. And you were totally okay with us getting out of those before you."

Lyra nodded. "Uh-huh. Potty training not supposed to be a contest. Mommy and Daddy say it not matter how long I take to get it right, and that there other ways to prove I big pony."

Bon Bon smiled as she looked to her special somepony. "You're always so forgiving, Lyra. You gave me a second chance that I thought for sure I didn't deserve. You truly are a one of a kind pony."

The padded unicorn then waddled over to Bon Bon, hugging her tightly. "Lyra love you, Bon Bon, always! Bon Bon first friend Lyra made in Ponyville that not care about Lyra's research and fascination."

Smarty Pants couldn't help but giggle. "Oh, so that way of sitting isn't just for show? Everypony always talks about your obsession with those other creatures that nopony's ever seen before."

"Smarty Pants!" Twilight shushed the doll. "It's not nice to make fun of other ponies for what they like or what they do!" She then secretly whispered. "Besides, you know those creatures are real. But I can't tell them about the mirror portal, it's supposed to stay a secret."

"Oh, right." Smarty Pants realized and quickly clammed up.

The padded alicorn then quickly sought to change the subject, knowing that Bon Bon was sure to press for more details (and probably Lyra too) if they knew what she knew. "So, anyway," She turned her attention once more to the earth pony mare. "Bon Bon, do you have any idea why Lyra chose to let Mommy regress her? Sounds like Lyra had a pretty normal foalgood. Her parents didn't pressure her the way some other Canterlot parents did. At least, from what little I remember of them."

Bon Bon shrugged her hooves. "Your guess is as good as mine, Twily. From what I can gather, Lyra was always something of a role model for ponies her age. She would always tell me how growing up she was frequently overhearing grown-ups praise her and telling their foals to be more like her. It wasn't just in potty training, either. Apparently, almost everything she did as a foal was something other foals should strive to be like: Walking, talking, you name it. And I guess she was just tired of all the attention, it made her feel like her foalhood was being controlled or dictated by others, even when it wasn't."

"Oh my gosh! That's awful!" Smarty Pants exclaimed! "Nopony should feel like their foalhood is decided for them by a bunch of poopy heads."

The earth pony mare just continued. "Yeah, well at least her foalhood was spent in one place where she could grow up with friends that didn't care what she was like. I can see how she might want to return to that time, to a time when ponies talked about her for good reasons and not for silly reasons. I know there's so much more to her than all her research. She trusted me with her secret, even when I was still keeping a secret from her."

Smarty Pants quickly deduced what Bon Bon was talking about. "You mean the whole 'Sweetie Drops' and 'S.M.I.L.E.' thing?"

Bon Bon gave a confirming nod, and let out a sad sigh. "Unfortunately, yes. There were so many times I wanted to tell her," Her lips quivered. "But every time I started to work up the nerve, I thought about how she'd react and what would happen if S.M.I.L.E. ever got re-established. I should've known I couldn't run from my problems forever, even if that's all I wanted to do."

"I remember Twily was really scared of the potty for a while after she flushed herself down it while trying to find out how it worked," Smarty Pants commented in reply. "And since I wasn't there for Twily when it happened, that just made it worse. I couldn't reassure her that she'd be okay. That's why I started singing to her once she was old enough for potty training. That way I could calm her down. I was so glad when it worked and Twily overcame her fear. It was like it never happened."

Twilight then chimed in. "And look at how well things worked out for you and Lyra, Bon Bon. You're still together despite everything. Lyra's told me and her old Canterlot friends how much she loves being around you now, whether you're working for S.M.I.L.E. or not. It reminds me a lot of the bond I have with my friends."

The earth pony mare with purple and pink locks smiled ever so faintly. "I'm flattered you think that way, Twily. Honestly, being in diapers again," She looked down at her own padding. "It's made me realize just how much I missed out on as an actual foal," Looking back up, she explained. "I already told you that my parents were S.M.I.L.E. agents when they had me, and that I was part of S.M.I.L.E. for as long as I can remember. But you don't know what that really meant. That meant my parents and I were constantly on the move, traveling from city to city and town to town. And it was always on short notice too."

Twilight and Smarty Pants exchanged mutual gasps of shock! And their gasps seemed to draw in Lyra, who waddled close and gasped too!

Bon Bon, undeterred, went on talking as she drew upon memories that had been locked away, waiting for the right moment and the right conversation to burst out into the open. "My oldest memories were of the traveling. We never stayed in any location for more than a year at most. It was at its worst when I was two and three. My parents were moving every other month it seemed, tracking down an elusive monster that had to be captured before it could pose a danger to anypony."

"Do you know what it was?" Smarty Pants asked the currently off-duty S.M.I.L.E. agent.

The earth pony mare with a cream colored coat put a hoof to her chin, trying to recall. "I think I overheard something about it being a cockatrice, or maybe a chimera. Whatever it is, it took nearly two years to be captured and sent to Tartarus. And while all that was happening, I was supposed to be in potty training," A frown formed on her face. "My parents only just started it when we moved for the first time. As you can probably imagine, with all the chaos going on in their lives as S.M.I.L.E. agents, things like potty training slipped through the cracks. It wasn't long before I started lagging behind my peers. But if I stayed in diapers for too long, ponies would start to get suspicious. So I had to learn as much as I could whenever I found the time, my parents didn't get to train me the way they wanted to. And I had to grow up before I truly felt like I was ready."

Twilight found herself unable to keep from tearing up. "That's so sad. It's like your foalhood ended in the blink of an eye, and you never got to say goodbye to it," Soon, she started crying, hugging the earth pony mare tightly. "Oh Bon Bon! If anypony should have a reason to go back to diapers, you'd be right at the top of the list!"

"There there, Twily," Smarty Pants tried to comfort the crying alicorn. "It doesn't sound like she's that upset about it."

Yet within seconds, Bon Bon was starting to cry too. And try as she might, she couldn't bring herself to stop. "It's not fair! Why did I have to give up my diapers so soon just so ponies wouldn't get suspicious?! Why couldn't I be allowed to grow up at my own pace and on my own terms?! Why did S.M.I.L.E. always have to take so much away from me?! It almost cost me my one true chance at happiness, to be with the pony I love the most!"

Even Lyra was crying and sobbing. "Bon Bon, your story make me so sad!" She replied in a foalish sounding lisp. "You no get to enjoy foalhood like I did."

"I guess that's one thing we have in common," Bon Bon admitted in between sobs. "We both have issues stemming from our past, and they all stretch back to when we were foals. If only we could've met then, we could've run away together and lived our foalhoods the way we wanted to."

Princess Celestia quickly came trotting over, moving to calm down the trio of crying foals. She lifted them all into the air with her magic and spoke softly to them. "It's okay to cry sometimes, my little ponies. Keeping your emotions bottled up inside you all the time isn't healthy. It's just like when you try to hold it in when you know you have to go potty. You can't hold it in forever, it has to come out sooner or later. And often, holding it in makes it worse than if you just let it all out. The same thing is true for your emotions."

Twilight seemed to nod quite slowly, nuzzling into Celestia's embrace. "You're so smart, Mommy. You know everything."

"Not everything, Twily," The sun princess replied with a sweet smile. "But when you've lived as long as I have, you tend to learn a lot. Besides, what kind of mommy would I be if I didn't know how to comfort my foals and cheer them up?"

Bon Bon blushed as she slowly ceased in her crying. "I'm so ashamed I did that. Especially in front of you, princess."

The older alicorn just waved a hoof. "Oh, you have nothing to be ashamed of, silly," She booped Bon Bon's nose with a hoof. "You're just a foal now. And crying is part of your character. Crying is how foals like you let Mommy know that something is wrong. Besides, don't you feel better now that you've gotten all that stuff off your chest?"

The earth pony mare paused, thinking over such logic. She was so used to masking her emotions as part of her cover. The idea of not doing so had seemed foreign to her until now. She had never given any thought to a "role" where expressing her emotions, whether real or exaggerated, was a good thing. But as she could clearly see with both Lyra and Twilight, they had no trouble doing it. Heck, Twilight was so taken up with the role that she'd not only given herself a nickname but also made her stuffed animal "talk".

Rather than set the now calmed big foals back down, however, the alicorn mare with a majestic white coat instead levitated them close to her teets. "Seeing as you're already so close to me as it is, I think now would be a good time for you all to get your nutrition," And she encouraged. "Go ahead, drink up."

Twilight happily latched onto one nipple and started suckling, closing her eyes as she timed her suckles to the rhythm of Princess Celestia's heartbeat.

With a cry of "Milkies!", Lyra did the same on her end. But she opted to keep her eyes open, and suckled much faster.

"Careful now, don't drink too fast," Celestia cautioned. "And save some for Bon Bon. I only have so much milk to go around, you know."

But instead, Twilight opened her eyes and removed her lips from the nipple she'd been suckling on, then said. "It's okay, I'm done. Bon Bon can take my place."

Bon Bon was understandably hesitant to drink breast milk, especially directly from its source. So she closed her eyes, trying to imagine she was a little pony again and being breast fed by her mother (one of the few memories from her foalhood not directly associated with S.M.I.L.E.). After a good deal of effort on her end, she was rewarded with the almost overwhelming taste of sweet, creamy milk.

The breastfeeding ended sooner than the earth pony would've liked, however. And she opened her eyes again in time to see her be set down next to Twilight and Lyra. "Alright, my little ponies," She declared. "What would you like to do now?"

Bon Bon looked around the room again. This time, she wasn't scanning for any sign of possible ponies listening in or otherwise observing her. She felt safe and secure in here with just Lyra, Twilight, and Princess Celestia. So she was instead taking in her surroundings more in depth. As she did so, an idea came into her mind. "I know," She proposed as she rushed to the bed and grabbed a pillow. "We could build a pillow fort! Lyra told me she used to make those all the time at slumber parties."

"Yay, pillow fight!" Lyra cheered and waddled over to join Bon Bon.

Twilight seemed to be satisfied with the idea too, turning to Smarty Pants as she asked. "Whaddya say, Smarty Pants? Wanna help build the fort?"

"Of course, Twily, you didn't even have to ask," Smarty Pants replied. "Since when have I ever refused to do something with you?"

"Never, that's when!" Twilight playfully giggled, kicking about in her pampers as she did so. She soon rushed over to the bed, grabbing a pillow as well.

Princess Celestia, for her part, smiled and clapped her hooves in approval. "A pillow fort sounds like an absolutely wonderful idea. But you'll need a lot more pillows if you're going to build a fort out of them," She quickly instructed to her charges. "Wait here, I'll go fetch some more pillows for you." And after lighting up her horn, she disappeared in a flash.

Undeterred by their "mommy"'s absence, the three big foals (and Smarty Pants) just took what pillows they could get from the alicorn sized bed and dragged them across the room. "Where should we set up the fort?" Smarty Pants asked Bon Bon.

Bon Bon shrugged her hooves. "I don't know. You and Twily know this place better than I do. Where do you think a good place would be to start building our fort?"

"I know!" Twilight exclaimed as an idea came to her! "We'll build it right across from the door! Then if anypony unexpected comes into the room, we can attack them!"

Lyra happily cheered! "Yay! Pillow fight!"

Bon Bon grinned. "I was hoping you'd say that, Lyra. But I'll have you know, I'm a pillow fighting champion. Don't think you can beat me just because you went to more sleepovers."

So Twilight, Lyra, and Bon Bon brought the few large pillows they'd managed to get their hooves on over to the other end of the room, facing towards the bedroom door. It didn't matter to them that the pillows they had on hoof were obviously not enough to construct a fort of any sort. They were just happy to start building it.

Princess Celestia teleported back into the room about a moment or so later, and in her magic she held what looked like a bag of very large pillows, all in colorful patterns and prints. She set the bag down next to the adult foals. "Here you are. These should be more than enough to construct a nice pillow fort. And you can use any spare ones for ammunition."

The earth pony mare let out a gasp! "You knew what we were planning to do?!"

Celestia replied with an innocent smile. "No, but I had a hunch you wouldn't be satisfied with just a fort. It must always have something to use to help defend it, after all."

Twilight and Bon Bon thus worked together for a while to build a pillow fort that occupied nearly an entire corner of the bedroom. Lyra and Smarty Pants helped a little, mostly with dragging pillows over for the other two to build with. But mostly, Twilight and Bon Bon did the work alone.

At last, the pillow fort was complete. It was so big that even Princess Celestia could step into its boundaries without destroying it. She smiled, admiring the careful crafted creation. "Wow! This is the best pillow fort I've ever seen! You foals have clearly outdone yourselves!"

Twilight beamed with pride. "You like it, Mommy?"

"Like it? I love it!" Celestia happily exclaimed! But then she sniffed the air as a familiar stench reached her nostrils. In a playful, motherly tone of voice, she declared. "Uh-oh, I smell stinkies. I think somepony worked a little too hard to build the fort."

"Who's the stinky one, Mommy?" Smarty Pants asked the sun princess. "I know it can't be me."

Celestia chuckled. "Of course it's not you, Smarty Pants. And I know it wasn't me," She continued sniffing the air as she trotted around the fort, trying to pinpoint the source of the stench. When she got near Twilight, she swore the stench of manure and methane was stronger. But she still opted to pass by the padded alicorn and inspect Bon Bon and Lyra first.

Lyra's diaper was pristine, it still had yet to be used. And Bon Bon was only a little bit wet. So that meant it had to be Twilight. Sure enough, when Twilight's diaper was pulled back for an inspection, a faintly audible squishing sound could be heard as the padded alicorn's face turned bright red from shame.

"Sorry, Mommy!" Twilight apologized in a playful yet embarrassed tone of voice. "I just didn't feel like using the potty, that's all. I'm not in trouble, am I?"

The sun princess shook her head as she lifted her foul smell charge into the air. "Of course not. You shouldn't feel ashamed about what you do or how you do it," She pretended to gag and wave a hoof. "But a little heads up the next time you decide to go poopy would be nice. And maybe we need to cut back on letting you drink my milk all the time, it seems like this happens a lot when I breast feed you."

"It does?!" Twilight asked in what sounded like sincere concern.

Princess Celestia laughed. "Oh Twily, don't be silly. I was only teasing you. There's no way my milk could make you mess yourself any more than anything else could. Besides, your body's surely gotten used to it by now." Then she carried the stinky princess out of the pillow fort, and to the changing table to be changed into a clean diaper.

Bon Bon and Lyra utterly enjoyed the rest of their day camping out in the pillow fort with Twilight. They even made a pretend campfire to tell stories around.

But of course, the day eventually came to an end. Lyra was still mentally regressed when she and Bon Bon left the castle that evening and returned to Ponyville.

Next morning, however, Lyra woke up and yawned as she opened her eyes. "Hey, Bon Bon," She greeted in a normal tone of voice. "So was our 'secret mission' to Canterlot yesterday? I wasn't too much of a hoofful in my regressed state, was I?"

Bon Bon shook her head from side to side. "No you weren't, Lyra. In fact, it would seem that even when mentally regressed, you still had enough self control to use the bathroom like a grown up."

Lyra let out an unhappy sigh. "Oh, that's a shame. I was hoping that even my potty training would leave me if Princess Celestia regressed my mind. Maybe next time I should have her turn me into an actual foal again."

"Only if I get to be regressed with you, Lyra," Bon Bon replied. "You looked like you were having so much fun in that carefree state of yours," Then she spotted something out of the corner of her eyes. It appeared to be a note of some sort resting on a small table. "Hang on, Lyra. I think Princess Celestia might have left something for us." She trotted over, picked up the note, and read it aloud:

Dear Bon Bon and Lyra,

I know I probably don't need to write this letter, but I want to thank you both for being such good playmates for Twily yesterday. You were probably some of the best playmates she's ever had. And it warms my heart to know that she's got so many good friends who can be trusted to keep her secret.

You two both strike me as ponies who know the importance of keeping secrets, and how much it can hurt when those secrets get exposed. So I know I can trust you both not to tell anyponies not already in the know about Twilight's secret. If you do tell, then far worse punishments than going back to diapers await you.

As promised, you'll both have something that you've been longing for. Bon Bon, I've already talked it over with S.M.I.L.E., and you are officially approved for time off to be with Lyra. You can pursue your relationship with her in peace.

And Lyra, I have enclosed something here that I think you'll quite like.

Sincerely,

Princess Celestia

By the time Bon Bon had finished reading the letter, Lyra had raced over to the stand and eagerly examined everywhere underneath it! Her eyes lit up like stars when she saw some rather large (and rather strange looking to Bon Bon) gloves! "No way! Princess Celestia came through!"

"Came through with what, Lyra?" Bon Bon asked.

Lyra quickly slipped the gloves on with her magic, then stood up on her hind legs and said with an exceptionally bright smile! "Fingers! This is it! This is the proof I've been searching for for so long! Humans do exist!" She threw back her head and laughed. "They all thought I was crazy. Well, who's laughing now?!"