Cannon Feather and Bucket Bridle were in the castle's playroom when Discord turned it into a giant nursery for Luna and Celestia. The two foal guards were busy with their "homework" trying to learn their shapes and colors. Cannon Feather was busy trying to draw circles with crayons while Bucket Bridle was using crayons to color by the numbers. Since their room was already quite, foalish nothing changed, and as a result, they didn't notice anything until they heard the baby alicorns wailing from above the castle.
Cannon Feather rubbed his head with a hoof and grumbled. "Wha's going on, is Mommy ok?"
Bucket Bridle stood up and shouted. "We gots to find tem and make suwe tey otay! We still woyal guawds, we gotta pwotect the pwincesses!"
The two waddled off together outside and gasped upon seeing the palace was quite different from what they remembered. It now had pink plush floors, and plushies and teddies were walking around the place. The two both were looking around the palace completely confused and amazed at what they saw.
They hurried along until they found a door labeled "Sun Butt and Moon Butt's Nursery." The two toddlers blinked in surprise and opened the door to find Celestia and Luna both sleeping soundly. Cannon Feather gulped as he whispered. "Hey, Bucket Bwidwe is tat ya mama?"
Cannon's adopted cousin gasped upon seeing Celestia sleeping soundly and slowly nodded as he babbled. "Yeah, it is. Wooks tey gots tuwned into babies too somehow. So what ya tink we can do to hewp tem?"
Bucket Bridle shrugged and babbled. "Not suwe but wets get going! We gots to hewp tem get back to being big ponies! Equewstia needs them!"
This caused the two alicorn foals to wake up while rubbing their eyes, and Luna cried in surprise. "Who woke us up?!"
The two regressed princesses turned their attention to the two toddlers. Celestia got up first, holding the bars of her crib while showing off the diaper between her legs. She shouted in surprise. "Hey Cannon Feathew, Bucket Bwdiwe! Ya two awe stiww hewe?!"
They both nodded as Cannon Feather babbled. "Yeah, we came to hewp when we heard ya cwies! Why ya babies?"
Luna blushed as she tried to cover her padded front with her hooves (to no avail) and explained. "Is a wong stowie, Cannon Feathew. Can ya hewp us? Twily changed owa diapees, and she messed up by putting us in ta wong diapees!"
The two colts nodded as they went about taking the two fillies out of the crib and laid them down on the nearby changing table. They then began to change their diapers and stumbled about, pouring an entire container of foal powder over the two. The regressed princess coughed and whined, kicking about as the colt littles strapped them in diapers with Celestia in a thick diaper with a sun printed on it, and Luna in a thick diaper with a moon printed on it. Afterward, they were raised back up, and Cannon Feather rubbed his head and asked. "So, what we gonna do, Mommy, and Auntie Cewwy?"
Celestia, happy to be back with a diaper with her cutie mark on it, was busily bouncing up and down. "Dun know." She admitted.
Luna babbled. "Ya know, why dun we try potty twaining? Kind of wike I potty trained ya, Cannon Feathew?"
Cannon Feather nodded. "Sure, wets twy it! Just gotta be carefuw, so ya dun get fwushed!"
"Bwight Wing's never gonna bewieve tat when he heaws!" Bucket Bridle laughed. "Gotta wespect the big potty."
"It not scawy!" Celestia huffed. "Ya dun have to wowship it!"
Luna just commented. "Tat why you caww them ouw othew thwones?"
Celestia just groaned, then they waddled out to the throne room where Celestia and Luna's thrones used to be. But now there were two training potties with their respective cutie marks on them. Bucket Bridle scratched his head and asked. "So wha happened to ya thwones? Tey twaining potties now?"
Celestia sighed. "It's a wong stowie, I'ww teaw ya watew, wight now wets twy going potty wike big ponies! Good ting I wemembew how to do it!" She waddled over to her training potty and blushed upon seeing her diaper was still on. "Uh, oh! Bucket Bwidwe, can ya hewp me with my diapee?" She asked her son, embarrassed at needing to have him help her instead of the other way around.
The little colt gave a nod, waddled over and helped Celestia remove the diaper before she plopped down onto the training potty.
Luna turned to Cannon Feather and asked him. "Can ya hewp me too?" The little colt squealed with delight as he waddled over and helped take off her diaper.
Soon the two little fillies plopped down onto the training blushing as they waited to tinkle, which they did. The two colts both cheered making the princesses happy and giddy kicking about in glee while shouting. "We went, potty!"
Cannon Feather then asked. "Gweat! Why don't we twy the big potties in the bathwoom? Maybe if ya gets potty twained on tem, ta speww wiww be gone wike in a faiwy tawe!"
They nodded in agreement, the princesses wanting to prove they were still big ponies and capable of big pony responsibilities. But suddenly, the training toilets turned into a giant, real toilets with Celestia's being pink and Luna's being purple! The two squeaked as they kicked about on the edges of the seats, crying out! "Eep, is so big! Hewp!"
Cannon Feather gasped as he tried to fly up to them. "I'ww save ya two, dun wowwie!" But it was too late; the two fell into their toilets with a big splash! Cannon Feather shouted! "Bucket Bwdiwe, thwo something ovew hewe so tey can swim! Quickwy!"
Bucket Bridle took the two diapers the princesses left behind and shouted. "Use tese!" He threw them at Cannon Feather, who snatched them up and threw one in each toilet. The foals grabbed onto the thick diapers that expanded in the water as they began to float above the water, gasping for breath and kicking about.
Luna was quite scared as she shouted. "How do we get out of here without getting fwushed?!"
Celestia cried. "Not suwe! We dun know how to fwy yet and we soaking wet! But I dun wanna go down ta howe!"
Cannon Feather turned to the diapers as he noticed they were expanding, sucking up the water. He shouted at the princesses. "Use ta diapees! Cwog up ta toiwets! It wowked fow me once!"
Luna and Celestia shrugged as they took their diapers and immediately plugged them into the holes.
Bucket Bridle then flew up and shouted at Cannon Feather! "Wha ya doing?! Tey need tose diapees!"
Cannon Feather just went to the lever of the purple toilet and shouted. "Ta diapees awe gonna cwog up the howe! When we fwush ta water wiww come down and tey wiww wise up!"
Bucket Bridle gasped and squealed! "Ya tink that wiww wowk?"
Cannon Feather nodded. "Wemembew ta time Bwight Wing fwushed his diwty diapee down the toiwet and it fwooded the bathwoom? Diapees dun fwush. And tese diapees wiww wowk ta same way."
Bucket Bridle nodded in agreement, that made sense. He could even remember how furious Celestia had been to discover the flooded toilet when Bright Wing had done that during their last sleepover at the castle. "Otay, wets do it!" He turned to the lever on the pink potty as he flew over to it. Looking across to Cannon Feather, they both pressed down at the same time, making the water rise. The two colts grabbed their scared moms but squeaked as the water started to pour out onto the floor, making a small pool. Cannon Feather and Bucket Bridle waddled across the floor and got onto a giant toy boat that was seemingly coming out of nowhere, watching as the toilet water steadily rose.
Cannon Feather and Bucket Bridle began fighting and shouting about who should be captain of their ship, while Celestia and Luna gulped knowing they were going to be in big trouble with Twilight for this!
Twilight (unaware of what was happening miles away) was quite nervous while standing in front of a podium, looking over the ponies of Canterlot. She was quivering as they looked up with confused looks, all waiting for her to explain what was going on. "All you need to know is that Celestia and Luna have regrettably been turned into foals. They will be like this for a month, and until then I will run things. Any questions?"
The ponies all started and demanded more answers. One shouted! "Why did the sun and moon turn into diapers and go all crazy?!"
Twilight squeaked and stammered. "Uh...well...I don't have a lot of answers for that right now. But I promise that I will do better in keeping Luna and Celestia under control."
But suddenly, Moonlight Glimmer appeared and declared. "Everything has gone according to my plans! Don't worry, ponies of Equestria, I will now control things and turn all of you into foals. Nopony can stop me now! All your heroes have been reduced to helpless babies! I will be your mommy, and you'll hang on every word I say!"
The crowd screamed, and everyone gathered ran for their lives before the alicorn could use any of her magic. However, the magic exploded, and she squeaked as her body began to shrink, and her wings grew larger! She slowly regressed into an alicorn foal, looking at the thick diaper between her legs. She whimpered. "H...h...how did tis happen? Tis wasn't pawt of my pwans!"
Discord suddenly appeared behind the foal. He picked her up by the seam of her diaper and cooed. "Now now, Midnight. As much as I would love to see everypony in Equestria turning into foals, I think it might not work out as well as you think. I certainly don't need a kingdom of foals and only one mommy."
Twilight blinked in surprise and asked. "Discord, why would you do that? Midnight was responsible for the original foal pandemic!"
The lord of chaos shrugged his paws as he responded. "Well, I didn't do it for you if that's what you're thinking. I feel that there can only be one Lord of Chaos. And on top of that I want to regress ponies, but in fun and different ways, and not for malicious purposes like she did!" He held Midnight up further as he declared. "Now, I'm going to drop this little one off with a 'special princess' who wants to see her, then I'll continue to watch you try to care for Celestia and Luna. By the way, you might like to know that they're awake and are flooding the castle."
With a flick of a claw, he disappeared while Twilight roared, hearing what the foals were doing and ran back to the castle as fast as she could! "Oh, they are gonna be in so much trouble for this! They better not have done what I think they did!"
Twilight entered the palace and squeaked as she immediately fell into a giant pool of water with a big splash! The mare gasped, paddling about with her hooves as saw she saw that the entire ground floor of the castle was flooded entirely in water with two toilets in the back of the room! Said toilets continuing to pour water out, and strangely they seemed to be the same colors as the training potties for the regressed royal sisters.
"Celestia! Luna! Where are you?!" Twilight called and continued to swim through the water, until she came upon a plastic toy boat, with all four foals giggling as they were pretending to be pirates (Cannon Feather and Bucket Bridle even had eye patches and cardboard swords)
Dodging a blast of confetti from one of the cannons, Twilight's was able to get onboard the plastic toy boat. She eyed the foals and asked. "Alright, what happened? How did the entire castle gets covered in water like this?!"
Luna whimpered and began to whine. "We sowie, Twiwy! We just wanted to use our potties, and tey tuwned into big potties!!"
Celestia nodded and babbled. "Yeah, is twue. We wanna use ta potty wike big ponies, but ten everything gots messed up! We sowie!"
Twilight sighed as she looked around "At least this time nopony got flushed. Rarity mentioned how that happened with both of her foals, as well as Cannon Feather." She thought to herself. Then she saw a giant plug in the middle of the room. Her horn lit up and took it out! She squeaked as the water started to circle the drain, with the foals squealing as Twilight shouted, "Make it stop!" She closed her eyes as the water eventually was all drained away, and they plopped onto the ground, the foals bursting into laughter.
Twilight groaned as she took out some diapers and foal powder and began putting Celestia and Luna back into said diapers as she grumbled. "Look, I know this is tough for you two, being foals and all. But you can't go around flooding the castle with toilet water. Especially not to the extent you just did, turning the whole castle into a river!"
Cannon Feather waddled over and explained. "We sowie is not their fault. We put tem on the twaining potties; ten tey turn into big potties. We just wanted to hewp them potty twain."
"And Cannon Feathew made them fwood so we cowud save ouw mommies." Bucket Bridle explained.
Twilight gave a deep sigh, seeing that the training potties were now two big regular toilets. "Discord!" She realized. "He's going to mess with me now and make this ten times harder. I should've known."
Bucket Bridle blushed and asked. "Twiwy, what happened? Why is my mama a baby now?"
Twilight sighed, taking the foals over her shoulder. "Let's get you all something to eat, and I'll explain everything," And she turned to Celestia and Luna. "And I think we need to talk about you trying to do things without me around. I can't risk more accidents like this."
Celestia and Luna were now in their highchairs suckling on foal bottles filled with formula, while Cannon Feather and Bucket Bridle ate peanut butter and zapped apple jam sandwiches and drinking down sippy cups filled with milk. While they ate, Twilight explained everything that happened to Celestia and Luna and explained the situation with Midnight Glow as well.
Princess Celestia popped the bottle from her mouth as she rolled her eyes and babbled. "I dun know if I shouwd either tank Dissy fow stopping Midnight or spank him fow pwanking us wike tis!"
Luna nodded and replied. "Yeah, he nice and mean? What is tat wike? He just doing tis to watch us be foals?"
Twilight shrugged and sighed." I'm not sure what his intentions are, but I do know one thing. I can't handle four foals. After you're all done eating, I'm going to take Bucket Bridle and Cannon Feather to Cadence and Shining. I've sent them a letter explaining things."
The two toddlers cheered as Cannon Feather shouted. "Yeah! Can't wait to see Bright Wing!"
Bucket Bridle cheered. "I hear his daddy's marrying Caddy. He's gonna have a pwincess mommy wike us!"
Twilight nodded. "They're due to begin rehearsing for the wedding at the end of this month, so you two better be on your best behavior for them. Especially for Shining Armor, he's my B.B.B.F.F. So if you give him a hard time I'll know," She then took out a two-seated stroller and snapped Celestia and Luna inside making sure the straps were snug. Then she turned to the colts and cooed. "Now come on, you two can walk. So let's set off." She then strapped a giant diaper bag around her shoulder, straightened her apron, and started to lead the four foals out of the castle and into the streets.
Once out and about, Twilight blushed and kept her head down as she pushed the stroller through the streets of Canterlot. Many ponies gave her odd looks, but she did her best to try not to give out any impressions other than the fact that she was caring for the foals.
After a while they eventually came upon the house Shining Armor lived in when not overseeing the royal guard (usually whenever he couldn't bring Bright Wing to the barracks with him). And after Twilight knocked Cadence opened the door with a bright smile. "Hello Twilight, it's so good to see you!" The princess hugged Twilight in a huge hug and they emberced each other for a few moments. Then Cadence turned her attention to her foalified aunts who were blushing and scrunching their diapers with their forehooves as she cooed. "So these two are Aunt Celestia and Aunt Luna? My, they're just so cute!" Cadence nuzzled the two and blew raspberries in their tummies, making them giggle and squirm.
Luna cried out. "Hey, stop tat! Ya gonna make us pee!" It was too late, a pair of loud hisses emanated from the diapers.
Cadence dawwed. "Oh, that was adorable. It looks like my aunts are going to need lots of diapers," She then turned her attention to Bucket Bridle and Cannon Feather. "Alright you two, come on in! I haven't told Bright Wing that you were coming, so go surprise him!"
The toddlers both squealed as they ran into the house while shouting. "Tanks, Auntie Cady!"
Twilight chuckled, watching the toddlers run off before she sighed. "Thanks, Cadence, I wouldn't mind caring for all three of the foal guards, but these two are a hooful as it is!" She gestured to the alicorns.
Cadence waved a hoof. "That's alright; you're going to do fine, Twilight. Just try to remain calm and enjoy this. I know Shining and I will, as will Bright Wing. I can't wait to become his mommy officially," She then lit her horn and started to lift dozens of packages of diapers, drifting them underneath the stroller as she cooed. "I have so many extra diapers from all my years as a foal sitter. I think you can use a few."
Twilight blushed as she squeaked upon seeing how many diapers under her stroller. "I don't think I'll need that many diapers! Discord stocked the nursery quite well."
Cadence scoffed, as though offended at the very notion. "How could the Lord of Chaos know how to care for foals? Now, I'm not done," She cleared her throat, then lifted many jars of foal food, including Mashed Peas as both foals made gag sounds at that. She then lifted something very embarrassing; a milk pumping machine and cooed. "This is something I kept just in case if I ever had a foal of my own. I think you can use it for now if the need arises. It might not be a bad idea to talk to your mom about it; she did it for you and Shining a couple of times."
Twilight's face was a deep red as both baby alicorns burst into laughter. All the unicorn could do was stammer. "Th..thanks, I guess? I don't think I'll use it though. It looks uncomfortable."
Cadence patted Twilight on the back and reassured her. "Hey, I said you're going to do fine, and I mean it. Now, I have one more thing to give you before you leave. This is something Shining says has helped him a lot with raising Bright Wing," She then took out a giant book that read: How to Care for Foals: The Ultimate Guidebook on Child Raising. The mare then continued, "This has everything you need to know, and knowing you, I bet you'll read it all in a few days." She stuffed it under the stroller.
Twilight looked up at Cadence. "Thanks, I appreciate this. And tell Shining I said hello."
Cadence gave a nod. "Will do. Now do me a favor and please take pictures! I wanna see some super cute photos of those two in diapers! It's not like they had cameras a thousand years ago!"
Twilight smirked, looking down at Celestia and Luna who were both squeaking at what Cadence said. The unicorn snickered. "Oh yes, I'll be sure to get some very adorable pictures and make an entire photo album." She then took the stroller and began strolling back to the castle with a bit more confidence. She could handle this.