Tinker's Foalish Vacation

by LeyenEnyo

Rating: teen
Tags: Original Character, Fetish, Comedy, Tragedy, Slice of Life, My Little Pony: Friendship is Magic
Length: 9055

Mindset convinces Tinker to join her in a trip to Fountonia, but upon drinking the regressive water, Tinker's old memories begin to surface. Memories he forgot long ago for good reason...

Tinker gets a letter from Mindset asking him to join her on vacation. Though hesitant upon learning where, he agrees to join his sister in a relaxing, (and regressive,) stay at the Kingdom of Fountonia, a kingdom inhabited by foals. After meeting some friends from her last visit, the two drink from the regressive water as they both return to their days when Mindset was just born.

Tinker, now as a seven-year-old, begins helping his now newborn sister, but as time passes, old memories he had long since forgotten begin to resurface, and he soon questions whether he was always the good older brother he remembered himself being, or if these pleasant memories only hid his true thoughts and feelings towards his sibling.

This story contains Diaper Usage, Regression, and some Mature Themes. If this doesn't interest you, might I suggest some good anime?

Published 2020-05-02 15:50:01 UTC
Last updated 2020-05-02 15:50:01 UTC

Prologue: Preparations

The grass field was quiet. Tranquil, even. A lone blue unicorn pony laid on the grass as she stared into the sky, not a cloud in sight. She gave a comfortable sigh as she closed her eyes and listened to the sounds of the wind, her brunette hair waving. Her breathing slowed as she relaxed and began to drift into unconsciousness.

Her sleep, however, was short-lived as a strange giggling was heard. Opening her eyes, she looked over the area and saw the source; a puddle that rippled with each giggle, giving a sort of echo like it were a portal to another world. One would ordinarily find such a thing perplexing and even worrying, but to the pony, it was as normal as looking into a door. She joined in the giggling as she got closer, a telltale crinkling of plastic being heard from the diaper she wore. Peering into her reflection, she saw herself as an infant, extending a hoof to her adult self. With a smile forming, she stuck her hoof into the liquid mirror and felt a tug from her reflection, going into the seemingly small puddle only to appear in another reality entirely.

The new realm appeared as a nursery, one filled with toys and furniture a baby pony would need. The little foal she saw was nowhere to be found, but one look at the mirror told her where she went. Now, she was the foal, and she enjoyed every minute of it. Hearing hoofsteps, she turned to the nursery door and saw a cocoa brown pegasus pony that towered over her, but her demeanor was far more gentle and caring. “Well, looks like my little Mind has returned,” she said with a warm smile.

“Cocoa!” was all the little unicorn spoke before hugging her loving caretaker, one that the older pony returned lovingly.

“It's been a while, hasn't it? You must be hungry.” The pegasus lowered herself to the floor as she presented her barrel, her mammalian features exposed for the infant. Without a second thought, the little pony placed her lips onto one of them and began to suckle, her mouth filling with sweet milk that flowed down her throat with ease. As she drank, her body naturally decided to make room by emptying whatever contents were in her before; her diaper swelling and expanding to accommodate the mess. Cocoa giggled before saying, “Well, looks like you'll need a new diaper when you're done.”

The baby pony simply continued, not even noticing the additional weight and warmth in her crinkly baby pants. She was far too invested in filling her belly with sweet milk. After another five minutes or so, the little foal finally had her fill as she gave a soft burp and sat down on her rump, unfazed by the squishing contents beneath her. She yawned as she was lifted up in the air by a wing and brought over to a nearby changing table, knowing what was next. She happily obeyed as she laid on the table and remained still as Cocoa went through the usual process of changing a diaper, only moving to put a hoof in her mouth to teeth on. This was soon interrupted by a pacifier being put in her mouth by Cocoa as she did the final touches and wrapped a clean diaper on her. Next came a sleeper that had her favorite bear as the design, as she put her hooves through the legs before it was zipped up from the back.

“Now, I think it's time for a nap, with your little baby belly full of milkies,” Cocoa said with a bit of cooing as she gently took her charge to the nursery's crib and covered her with a foal blanket. “Sweet dreams, little one. I'll be waiting for you when you get here.” Before leaving the nursery, she turned on the nightlight and closed the door.

The little foal felt at peace, knowing her mommy, (or rather, her “other” mommy,) was waiting for her. Before she drifted off, she looked at the nightlight, and pondered why it was brighter than usual. Normally, it was just a gentle light to scare away the dark shadow monsters, but it seemed a little too blinding this time. In fact, it seemed to only get brighter the more she looked at it, until the whole nursery was enveloped in light. Closing her eyes, she could no longer stare at it until eventually a loud ringing noise started sounding, almost... Almost like a...

~*~

BRIIIIIIIIIIIIIIIIIIIIINNNNNNGGGG!

The unicorn, back in her adult form, stared at the alarm clock as it sounded, taking a few seconds to try to silence it with her magic. After doing so, she stared at the window, the sun's light shining right into her eyes and reflecting off the ring she wore on her horn. “Well, that explains the nightlight,” she said groggily before removing her blanket. She gave a quick stretch to her limbs and muscles before looking down at her protective undergarment, clearly stained yellow from her accident earlier, with a noticeable mass squishing beneath her. “That also explains why I was feeling that warmth, not that it's anything new.”

“Talking to yourself again?” piped up another pony that laid next to her, her golden hair being the only visible thing from under the covers.

“Just talking about an odd dream of mine.” Though she wasn't wrong about its oddity, she didn't say such a thing with disdain or worry. “It was about me being a foal again.”

“Oh, really? I never would have guessed,” the other mocked with a slight giggle.

“Oh hush, you.” The unicorn smiled as she gently planted a pillow on her friend's head. She immediately got up from under the covers, her green coat visible along with her own protective garment, also stained yellow. “You're just as likely to have such dreams with your crinkly butt.”

“Eh, I'm not worried. I just know you're more of the foalish type than I am.” She smirked and stuck her tongue out. “Besides, I only need them at night, unlike a certain blue pony I know.”

“Keep that up, and you'll be wearing them much more often.” The unicorn simply rolled her eyes and gave her friend a kiss on the cheek. “If you know what's good for you, you'll respect said pony, right Emerald?”

The green earth pony chuckled. “Yes, Mindset, I will.”

It wasn't long before the two were up and changing their clothes, (and diapers,) and got themselves ready for the day. Emerald prepared a kettle of water for some coffee as Mindset showered and dressed up for work. She paused, however, when she noticed the calendar, and expressed worry as she noted that Maternal Mare Day was coming up soon, reminding herself of her marefriend's unfortunate circumstances. Her thoughts were interrupted as Mindset entered the kitchen, dressed in her business suit and skirt, diaper only slightly exposed. “Um, don't get mad, but next week is... Well...” She hesitated to finish that sentence.

Mindset, however, felt anything but anger. “I know, but you have nothing to worry about.”

Emerald felt confused, as this holiday was practically the bane of Mindset's existence, until she recalled her story of last year. “Oh right! I almost forgot about that.” She felt a weight lifted off her shoulders as she finished making coffee and poured two cups for them both. “So, thinking of going there again this year?”

“Of course. I need the therapy.”

“Go figure, the therapist needs therapy,” she joked.

“Hey, even a pony like me needs it. Wouldn't want me to be that grumpy again, would you?” Emerald flinched at the idea, especially since she was partly responsible for her marefriend's hatred for the holiday. “You know, I was thinking of bringing a friend with me...” Mindset gave her a humorous smile as she awaited her answer.

“Ha ha...” She sarcastically laughed before taking a sip of coffee. “You know I'd love to join you and be a foal again, but I can't because I have that gem shipment I need to deliver. Now that they're cut to perfection, they need to be sent to jewelers all across Equestria. I can't stop doing any of that just for some baby playtime.”

“I know. I just like to tease the idea to you.” Mindset took a sip herself. “Besides, I was thinking of another pony to join me. One I hadn't seen since Hearth's Warming.”

“Your brother, I assume?”

She gave a nod. “I've been noticing him becoming more engrossed in his work, like I was last year. I think a break from his inventing would do him some good.”

“It's your call. Just be sure you both take care of yourselves, and don't go becoming a permanent baby. I may not mind changing your diapers from time to time, but I certainly don't want to have a baby marefriend. Ponies would get the wrong idea about us.”

“Oh don't worry, the 'Perma-Youth' water was kept closed off for everypony's safety, and they're keeping it under constant surveillance so ponies don't drink any of it. At least until the river reaches the falls, where the churning dilutes the water's effects.”

“Yeah, well, I still don't want you to take any unnecessary risks, from one pony to another.” Emerald gave her a quick peck on the cheek. “Although, I wouldn't mind some photos of your trip. I'd bet you'd look just adorable in anything.”

“Right, I'll bring Robu too, since he's been wanting to see Glitter.”

The two continued their conversation until Emerald finished up and left for work. Mindset, though, took a moment to write a letter to her brother, hoping he'd be more than happy to meet her. She then took a sheet a paper that read “Vacation Request” which had been filled out and given a seal of approval. Only a couple days to go.

Chapter One: Inventing an Excuse

That was a day ago. At the time, I didn't know what was going on in my sister's life. At least, not as much as I used to. Having grown up into the mare that she is, I didn't think she would need somepony like me to care for her anymore. Still, I did enjoy our conversations whenever we did meet, which was surprising when I actually received that letter.

I was working on a new design for Silly Filly, the company I work for, that would make diapers more absorbent without as much “poof” in them. I know some ponies like that sort of thing, but this was for those that preferred privacy for their condition, much like my sister. She was always shy about it, trying her best to hide it, even if it did occasionally peek out of her skirt. Lately, though, she had been much more comfortable and calm, not letting it bother her so much. I guess she really was growing up.

On top of that, I was also trying to create a new method of transportation for us earth ponies and unicorns; one that could travel to great distances in a short span of time. Sure, there were hot air balloons, air ships, and pegasus-drawn chariots and carriages, but they were usually limited to a set speed: slow. The only one with any difference would be the chariots and carriages, but those were limited on the strength of the ponies pulling them, and had a small passenger limit. I was thinking of a design that could carry large numbers of ponies with speeds that could break records, and perhaps even be just as fast as the Wonderbolts. Ambitious, I know. Possible, uncertain. Still, one can dream, and inventors are about using their imaginations.

However, my well of imagination had dried up, leaving me with little to show for it. Every attempt I had made ended up blowing up in my face. (Literally, I might add.) I was just about to make one last attempt before I heard a knock on my workroom door. “Hold on for one moment!” I called, letting the pony behind aware that I was coming. After shutting the machines down for safety reasons, I opened the door and saw my loving unicorn wife, Thursday.

“Hope I'm not interrupting anything, but yoooou got a letter,” she sang a bit.

“Really? From who?”

“Your sister, apparently. It has been a while since you last talked to her.” She gave me the letter, and I felt a pang in my heart about not keeping in touch with her.

“I know, but she knows how important my work is. I can't just stop what I'm doing for some quality time with her. I'll make it up to her, I promise.” As I spoke that, I read the letter and found myself shoving my hoof in my mouth.

“What's it say?”

“She wants me to meet her in Canterlot. Apparently, she's going on vacation and wanted me to come with her.”

“That's perfect! Now's your chance to reconnect with her and even relax.”

“Thursday, I just said I can't leave. My work is too important. Besides, I'm on the verge of a breakthrough.”

She rolled her eyes. “That's what you said last time, and look what happened then.”

“I only singed the carpet a little...”

“And almost blew up a chunk of the wall.” I winced at that reminder. “Tinker, you can't just expect to create something great when you're tired. I mean, just look at yourself. You've got dark circles under your eyes, and you look like you haven't slept in months.”

“I don't look like that.”

“Oh really?” She used her magic to pull out a mirror from a drawer. “Do you still think that after looking into this?”

I peered into it and noticed what she meant. “Ooh... I do look rather bad...”

“Ya think?!” She put the mirror back in the drawer and gave me a pleading look. “Please go, Tinker? You need this.”

I admit, when she got like this, it was hard to argue. “Okay, I'll go.”

She gave a gentle smile and kissed my cheek. “I'll get you some things you might want to take with you.” She left to take care of that.

“Well, what's the worst that could happen?” As if to answer, my latest attempt sparked and started a small fire. “Oh geez!” was all I said as I put the flame out.

~*~

The next day, I took a train to Canterlot, where I expected Mindset to be waiting. However, upon my arrival, she was nowhere to be seen. There was one pony that I did see, though, and I knew her well. “Emerald, so nice to see you,” I spoke in slight sarcasm.

“Gee, good to see you, too,” she returned, no doubt feeling a little hurt by my tone of voice. I couldn't understand why Mindset chose her, of all ponies, to have a romantic relationship with. Sure, she's changed much since I saw her as a filly, but the prejudice I had for her ran deep. She was the sole cause of my sister's magical mishap all those years ago, and I don't recall her ever apologizing, though she speaks otherwise. Not to mention all the times she bullied her because of Mindset's incontinence. Nevertheless, she was now a member of our family, and though I hated the idea, I didn't intervene. “So, just going to stand there, or are you going to follow?”

“Huh?” I shook my head as I returned my focus to the conversation. “Oh, uh, right behind you.” Carrying my luggage, the two of us walked through the castle town and market. “So... How are things with you two?” I tried my best to sound nice.

“Just fine. Mindset has been having strange dreams of being a foal, but fine.”

“Oh really?” I raised an eyebrow, which she took notice of.

“Hey, I'm not the one who planted the thoughts into her head! She came to them of her own volition,” she defended. “Besides, she's not the only one who sleeps with pampers to bed.” A hint of pink appeared on her cheeks as she mumbled that out.

“Right, your weak bladder still hasn't grown into the big filly bladder it was supposed to be.”

“Hey, just like your sister, mine's a medical complication, okay?!” Her anger began to rise. “Ugh, why do I care what you think? You spend all your time making diapers; who are you to judge?”

“Fair point. Still doesn't absolve you of all the trouble you gave my sister.”

“Oh for the love of Celestia, will you just let it go?! I told her I was sorry, I swear! Besides that, I was just feeling insecure about my own problems, and I took it out on her. I know it was wrong, but she has forgiven me.”

“But I haven't. You nearly put her into a permanent magic-induced coma that ultimately could've lead to her demise. Had I not create that inhibitor ring of hers on her horn, you would've likely spent some time in Tartarus, if not the rest of your life.”

“Tch...” She simply turned away in frustration. “You think I don't know that? When she was lying in that bed, all I could think about was what would happen to her, and what would happen to me. When I heard rumors of the doctor wanting to...” She couldn't bear to finish that sentence. “Look, it doesn't matter now. I couldn't care less about whether you forgive me or not. She has, and I love her greatly for it.”

“Is that before or after you continued to bully her?”

She didn't answer but continued to walk. “If you don't think her and I are meant to be together, then why didn't you stop us?”

“Because I'm not the one in charge of her life, especially her relationships. Interfering in that regard would only make things more complicated. Besides, she's strong and smart enough to know how to deal with bad relationships. If there's something she sees in you worth having, I can't tell her 'no'. Doesn't mean I have to like them, though.”

“Noted.” She sighed as we made it to their house. “Mindset, your brother is here!”

“I'm upstairs, getting my stuff packed!” I smiled as I walked up to her room. “Hey, Tinker. Just give me a moment. I'm trying to... Get... This... Closed...” She struggled to finish her sentence as she tried to close her suitcase.

“You sure you don't need help?” I gave her a curious look.

“Oh no, it's fine. I just need to-” Her suitcase snapped open and clothes flung out. To my surprise, however, many of the clothes were sized for foals, and were oddly infantile for her. Even her diapers were foal-sized, save for a few that were scattered in the mess.

“Uh, Mindset, are you expecting a baby or something?” I hoped the answer was 'no', if only because I knew she'd have to find a surrogate stallion to... I'd rather not explain.

“Uh, no, I'm not.” I felt relieved, but she still seemed nervous. “It's for our vacation. I'm going to be a foal throughout it.”

“What?” I didn't understand.

“Well, I was going to wait to explain this, but I plan on going to the Kingdom of Fountonia.”

“Fountonia?” It took me a moment to remember what that was. “Wait, is that the kingdom you discovered last year? The one that turned its citizens into actual babies?!”

“Don't get mad, but I was kind of hoping you'd join me this time around.”

I felt my eye twitch. “No, no way! I'm not turning into a foal!”

“Tinker, please? I know it's a lot to ask, but this is really important!”

“How so?”

I saw a bit of hesitation from her. “Well, I was hoping you'd help take care of me, like you did before. Princess Glitter was good, but being a foal herself, she doesn't have the best experience.”

“Take care of you? You mean as I am?”

“If you want to. Personally, I was thinking you'd be seven years old, just like when I was an actual baby? It would help with the immersion.”

“Immersion?! Look Mind, I know it's been hard for you since...” I paused as my tone shifted a little. “Since you didn't get to meet Mom, but asking me to just pretend this other pony you told me about is our mother, I don't know if I'd feel comfortable.”

“I know how you feel. I was like that too, but Cocoa is a really nice pony, and I'm not asking you to forget about our actual mother. Just help me fill the void that's in my heart. You remember what I was like before; you know how irritable I was when this holiday came around. I'm just asking you to help me, please?” She gave me the ol' puppy eyes trick, which only made me raise an eyebrow. Still, I could tell she really needed this.

“I don't know, Mind, you're asking me to take some time off to help you be a baby, and even asking me to regress with you to when I was a colt. That's a lot to take in.”

“I guess...” She paused, however, and soon a smirk formed on her face. “You know, you could always go for business reasons...”

“Business reasons?”

“Well, they don't have Silly Filly brand over there, and they need somepony within the company to help market it to them.”

“Are you really trying to convince me to go with that little ploy?”

“I don't know, am I?” She gave me a knowing look. “I know 'upper management' wouldn't mind getting some new business outside of Equestria. You could even get a raise or a promotion...” A wink to add to her convincing argument.

After some actual thought, I considered the scenario. “Just seven years?”

“Yep.”

“No diapers for me or anything?”

“Not unless you want to.”

“And for just how long?”

“A week. I considered longer, but I figured you probably had a lot to do and couldn't do anything longer than that.”

She wasn't wrong. I really did need to get back and finish that invention of mine. Still, I did need the holiday. “Alright, I'll do it. Just promise me you won't try anything weird.”

“I guarantee that you will not regress any further than that. Cocoa and Glitter have learned their lesson last time, and they've been publicly open about the water's magical power to all who visit, only regressing ponies that actually want to regress.” It felt comforting knowing that. Still, somewhere in the pit of my gut, something told me that this wasn't going to be as simple as that.

~*~

“Now remember, don't drink more than you need to. You may be my children, but I don't have the years to raise you and Tinker back up again.”

“Daddy, relax, they have aging water that'll bring us both back to our normal ages,” Mindset stated to our father, Heart Shield, who saw us board the carriage pulled by the Pegasus Transport Unit. One of the benefits of having a General of the Royal Guard as a father: you have your own personal escort.

“I'll make sure that she doesn't overdo it,” I told him.

“I'm counting on you, Tinker. I don't know this 'Cocoa' as much as Mindset, so I need you to keep an eye on things and make sure they don't pull anything like they did last time.”

“Daddy, please, I promise you they aren't going to do that again. They learned their lesson, and don't plan on doing it ever again. Besides, if they ever do try it again, I'll stop them one way or another. I'm immune to the water's mental regression, remember?”

“Only because your psychology-based magic acts as a protective shield,” I reminded her. “That doesn't mean they can't do something about that, or try a different strategy.”

She groaned. “Will you two please stop being so paranoid? I promise you, both of you, that nothing will go wrong.”

“General, sir, we're ready to go anytime,” one of the pegasi stated, saluting in the process.

A sigh escaped our father. “Very well. Nova, Blue Skies, I leave you in charge of escorting them. Take good care of them.”

“Yes, sir!” They both saluted.

“Wait!” All present turned to see an earth pony approach. “Mindset, I have something for you.”

“Emerald? What are you doing here?”

“Heh, you didn't think I'd just let you go without one last goodbye for the whole week?” She gave Mindset a peck on the cheek. “Besides that, this is for you.” She pulled out a large book that looked colorful and had some pictures of a familiar bear on them. “For you and any foals wanting to read it.”

Mindset gasped. “Is this the complete Cuddle Bear Collection?! This must have cost quite a few bits to get!”

“It was worth it for your smile.” Emerald glowed with pride. I just rolled my eyes. “You also forgot a certain someone...” Upon saying this, a mechanical butterfly flew out from behind, giving Mindset a piece of his robotic mind.

“Oops! Sorry, Robu; guess I got so carried away by having Tinker here, I forgot to wake you.” She blushed with embarrassment as he landed on her horn with a huff.

Ah, Robu. I remember when her and I built him. Although he's Mindset's pet, he's been a part of our family for years. A mechanical marvel of engineering and magic, Mind and I pooled our skills into building a sentient android capable of complex thought and emotion. A true living Artificial Intelligence that would make all others pale in comparison.

“By the way, Tinker, I have something for you, too.” She pulled out a small toolbox that looked filled with various tools. “I figured they only had toy tools over there, and since you're such a handipony, you'd want to have some real tools to work with.”

“Gee, thanks.” I admit, I was surprised by the gift, but I wasn't about to give her any appreciation of her act.

“Glad I could help...” she said with a hint of frustration.

Mindset, of course, noticed the tension between us. “Ahem, well, if that's it, then shall we go?” she asked the two pegasi.

“Sir?” one of them asked. Our father simply nodded.

“See you in a week, Emerald!”

“See ya, Mind! Have fun!” The last words we heard as the carriage flew into the sky.

“You know, Tinker, I know you two aren't on friendly terms, but I'd appreciate it if you could try to get along with Emerald.”

“Right, the pony who only bullied you into a coma.”

“That was years ago, Tinker. She's changed since then.”

“I know that, but that doesn't mean I'll forgive her. Sorry, Mind, but that nerve is deeply rooted.”

“...I suppose it is...” The ride to Fountonia was rather quiet, and Mindset seemed nervous throughout, no doubt because of the bumpy ride. I took the time to consider this when coming up with my new idea.

The carriage only stopped at a pegasus rest stop, which gave us time to relax a bit, even if we were stuck on a cloud. “Hey, Tinker, I need a change.”

I looked to my sister as she had a pleading look. “You want me to change you? I thought you'd want to do it yourself.”

“Were this any other trip, maybe, but since we're heading to the 'Kingdom of Foals', I thought it would be good practice if my big brother changed my diaper like he did back then.”

I admit, it did feel nice for my sister to need me again. Like a part of me that had been taken away for a long while had finally returned. “Sure, I'd be happy to.”

I won't go into the details, for privacy sake, but the change was successful and Mind's pants was fresh and clean for the time being. “Ah, much better. Thank you.”

“You're welcome.” I started getting bored as we waited. “So, about this Cocoa...”

“Yes?”

“How exactly did she convince you to be her baby?” I had heard the story before, but some of the details seemed a bit strange.

“Well, it wasn't really her. It was Mom who convinced me.”

“Say what?!” That caught me off guard.

“I know, it sounds weird, but she appeared within my subconscious.”

“You mean like how you channeled her that one time in Neighpon?”

“Yeah, exactly. I guess this ring of mine sort of called out to her in my time of need.” She motioned to the inhibitor ring on her horn. Hard to believe that it was made of Stygian Iron, something I came across by complete accident. I never did manage to find that vendor and ask how he got it, considering the ban on such metals. “Anyways, she came to me and told me it was okay. She gave me her permission to let go and move on.”

“You sure it wasn't Stockholm Syndrome?”

“I'm serious, Tinker,” she said in a deadpan voice.

“So am I.”

“Well, regardless of what you think, the treatment has been helping me cope, and I'm much more happy than before. It could even help you if you gave it a chance.”

“Me?”

She gave me a knowing look. “Oh, like you weren't affected by Mom's death.”

“Well, sure, but not to the same degree as you. I didn't become bitter about Maternal Mare Day and took out my frustration on ponies.”

“Touché. Still, just give it a try. You might enjoy it more than you think.”

“Right...”

Soon enough, the two pegasi returned, and we were on our way. Not much happened after that, though I did get more ideas about my invention.

~*~

As we arrived, we looked out the window to the kingdom itself, and my jaw dropped. “Whoa, it's huge!”

“I think it's bigger than last time!” Mindset was practically bouncing in her padded seat, and I didn't mean the ones on the carriage. The kingdom was full of baby ponies, and from what we saw, other baby creatures, such as hippogryphs, gryphons, changelings, kirins, even a couple dragons. “Last time I was here, this place was ponies only, but there's much more variety now that the secret is out.”

“No kidding.”

The carriage landed in front of the castle, which was built with toy building blocks, just like Mindset had said in her story. She was quick to get out, if only to see if any recognizable faces were around.

“Doctor Mindset!” I turned to see two little ponies in what appeared to be play-armor approach my sister. The distinct sound of crinkling plastic from the two made me understand that they were both in diapers.

“Nimbus! Cirrus!” She immediately hugged the two. “It's great to see you again! You both look like you got taller!”

“Nah, we just drank some aging water. We still have to wear diapers, though, since it's still part of our guard uniform,” one of them spoke as he sat down on his cushioned posterior.

“Not that it matters. The two of us decided to just forget potty training anyways, since we're not going to truly reclaim control over it, and because nearly all residents here are diapered, as well,” spoke the other. “Not like it's vital here. Anypony could get by without that skill.”

“Very true. After all, just look at me.” She flashed her diaper without hesitation to them. While the three giggled from that response, I tapped my sister's backside to get her attention. “Huh? Oh right! Cirrus, Nimbus, this is my brother, Tinker. He's here to join me on this trip.”

“Nice to meet you!” the pony Mindset gestured as Cirrus spoke.

“So, you're here to relax as well, huh?” the other, Nimbus, asked.

“Only because my sister here was so determined to get me to be the older brother like when she was a baby. I mean, before all this.”

“Sounds to me like you aren't entirely happy being here?”

“It's not that I don't want to be here for my sister, but I'm just not really all that interested in being a seven-year-old again.”

“He just needs some time to get used to the idea. I did kind of spring it on him in surprise,” Mind assured.

“Well, not to worry, he will enjoy it. Especially now that Quick Beam has made a formula that can regress one's physical appearance, but not their minds.”

“Really?!” She seemed shocked.

“Yeah! Thanks to you, he and Glitter have been experimenting with the water, trying to find ways to make it more safe to drink and not have such drastic changes. They managed to find one that allows anycreature to be young again while still retaining their memories.” Cirrus bounced as he spoke.

“That's amazing! So no one will have to worry about losing their memories on accident.”

“That's the idea.”

“Yeah, that's great and all, but we should really start grabbing our luggage and get our rooms. The two pegasi behind us are starting to get impatient.” I pointed her to them and she blushed.

“Oh, right. Sorry you two, we'll get this stuff off and you can be on your way.” They nodded as we rushed to get our things, and it wasn't long before they took off, giving one last goodbye for the week. Cirrus and Nimbus had been waiting as we grabbed our things and followed them into the castle. “So, how is Glitter, anyways?”

“Same as ever. Loving her kingdom and people in a way that a child loves their mother.”

“Isn't it the other way around?” She raised a brow.

“Not in this kingdom.” The two began chuckling as Mindset followed along, giggling herself. I admit, given the circumstances, it was humorous.

“Seriously, though, she's just as surprised by how we've handled things with our memories back, and has grown to trust us with our knowledge,” Cirrus continued.

“It's like she's learning more from us rather than us learning more from her, and like a foal, tries to learn and grow to make us proud,” Nimbus added.

“That's not surprising. She is a foal,” Mindset remarked.

“True, but you can tell she's regained more of that adult personality, if only slightly. She still prefers diapers over toilets any day, but at least she's finally not afraid to show her true self.”

“Glad to hear it.” The two of us approached the main lobby and dropped our jaws. “Wha-what?! When did this happen?!” Before us was a statue of my sister, (as a filly, mind you,) with a plaque that read “To the one who freed us.”

“Yeah, we kind of considered you our hero, since you revealed the truth to us and gave the kingdom its freedom. Glitter was most relived to not have to keep such a big secret anymore.”

“I'm flattered, but a statue?” She was beet red from the attention.

“You don't like it?” Nimbus gave her a puppy-eyed look.

“Oh, Nimbus, it's nice, but I never really considered myself a hero. I was just trying to mediate both parties to ease the tension between them, just enough that they could both talk things through civilly. That whole 'memory restoration' thing I did was an accident; one I wasn't initially planning on doing at first. Still, it was nice of you and your kingdom to honor me with such a thing, but it feels too much for something so little.”

“So little?! You practically stopped a mob from turning the whole place into ruins, and talked them down from ripping our princess apart out of anger! That's not something that's considered small!”

“They have a point, Mind. You did go above and beyond to help this kingdom and solved it's secrets. I think it's fine.” I had to admit that a twinge of pride for my sister filled me.

“Well...” she modestly thought. “I mean, I suppose I did save this kingdom... even if I was the one who technically caused the problem to form in the first place.”

“Nah, the real trouble starters were those two twins. They fanned the flames that day.”

“Ugh, the Flim Flam Brothers...” Mindset said with a grimace.

The Flim Flam Brothers. Even I groaned hearing their names. It was no surprise that they were involved. The two scam artists were always causing trouble somewhere, but to steal one of my inventions, albeit one I considered a failure, made me boil in anger. I never wanted to punch them so much in my life until I heard my sister's story. It was one thing to take my work and use it as a marketing ploy, but to stage a coup against a kingdom for the sake of reaping the rewards and revenge was just vile. “Speaking of, are those two still here?”

“No, unfortunately...” A new voice spoke out, causing us to turn to a pegasus mare with a light blue coat and dark blue mane. “Sadly, while we weren't expecting it, they drank some aging water and escaped. We haven't seen them since.”

“Yeah, those two have a knack for sneaking out of situations. They're more slippery than grease on a pole.”

“Frost Wind!” Mindset galloped to the mare and hugged her.

“Good to see you again, Doctor. Here for your therapy session?”

“Yep, and this time, I brought my brother with me!”

She gave me a nod and extended a hoof. “Frost Wind. I'm the adoptive mother of these two.”

I took her hoof in return. “Tinker. So, you're this competitive pony my sister told me about.”

She blushed. “Oh, she told you about that? Yeah, our little game with Cocoa and Glitter. I admit, things got a little out of hoof last year, so we're gonna try to make the bet more... lenient this time around.”

“That's good to hear. I can't wait to play, though I'll probably just fall on my rump a lot, since I'm going full newborn this time around,” Mindset said with a smile.

“Well, at least you'll be well protected with your diapers,” she joked. “What about you, Tinker? You going to take part in the games this year?”

“Well, I'm only here for Mind. She wanted me to be her big brother just like before, so I'm just gonna support her for now.”

“Alright, fair enough.” Our talk was cut short as a loud hissing was heard. The three of us looked to Cirrus and Nimbus who both sighed with a blush as their protective undergarments tinted yellow and sagged from the weight of urine. “Uh huh, couldn't hold it, I take it?”

“Sorry, Mom. You three were just having a fun conversation, and our diapers were just too tempting to hold it in,” Nimbus remarked.

“Why are you apologizing? We're wearing them for a reason!” Cirrus added, unashamed of his accident as he poked the swollen padding playfully.

“Your brother's right. Those things were meant for this kind of use.” Frost turned back to us. “Sorry, but I need to change their pants, before they have another accident and leak. Glitter's waiting for you in the throne room.”

“Okay. See you all later, then! Next time you see me, I'll be much smaller than you!” my sister shouted in excitement. With that, we split up as Mind led me to the throne room itself, though Mind's ears seemed to perk as Frost passed her, almost if she heard something faint from her.

I hadn't noticed before, but the décor of the castle was really foalish, which made complete sense. Pastel colors, playful looking rugs and carpeting, foalish artwork and even some foal-themed statues, like pacifiers, diapers, bottles, etc. The door to the throne room opened as we approached, giving us full view of it, which had several guards, (many around two to five years of age,) and a few servants that ranged between five to thirty years.

The moment Mindset stepped in, the entire room cheered for her return. Mindset, however, was completely bashful. “T-thank you, everypony, but really, it was nothing.”

“Mindset!” The next thing I saw was a little alicorn foal gallop full speed to my sister. Her lisp was a little bit hard to understand, though.

“Glitter!” The two hugged and laughed. “It's great to be back. I see this kingdom has grown quite a bit since I was last here.”

“In more ways than one, thanks to you. Creatures from all over are coming here! We've never been this big before!”

“Glad to hear it, though the statue I saw in the lobby was a surprise I wasn't expecting.”

“You like it? Nimbus and other artists worked real hard to make it.”

“I mean, it's nice, but a little much.”

“Here we go again,” I intervened. “You'll have to forgive her bashfulness. She's very modest about the whole thing.”

“Who are you?” Glitter tilted her head as she inspected me. Before I could answer, however, she spoke, “Oh, wait! Are you Tinker?”

“Huh? Uh, yeah. I'm guessing my sister told you about me?”

“Yes, and you look exactly like I imagined. Tall, responsible, and, um, kind of cute.” She said that last part with a blush.

“Oh, uh, thanks.” I felt awkward.

“My brother is here to join us this week.” My sister eased the conversation.

“Really? So, you'll be a baby, too?” The little foal vibrated her eyebrows in a knowing fashion.

“No, no, just to seven years,” I replied. “Mind here thinks it'll help the 'immersion' if I was at the age when she was born, playing as the big brother role like before.”

“Oh, that makes sense! This way, you two can relive your foalhood together!”

“That's the idea. Though, I'm curious, where's Cocoa?” Mindset looked around the room.

“Oh, uh, she's having one of those days.” The two of us blushed at the implications. Glitter soon followed when she realized what she said. “Oh, no, not one of those, I mean she's having one of those regressive days!” She corrected herself, allowing us both to sigh in relief. “She's been having some bouts of regression lately, sometimes regressing deep into foal age. A lot of ponies are nowadays, since we don't have to keep up appearances as much. A little aging water will bring them back, but it still tends to happen more often, and with some side effects to boot.”

“I see. So that's why I heard crinkling from Frost; she was diapered, too.”

“Yeah, a lot of grown-ups around here are finding themselves in need of protective underwear lately.”

“Well, lucky for you, we happen to have somepony who could help with that.” Mindset winked as she placed a hoof on me.

“Oh, right, your brother works for, uh, what was it?”

“Silly Filly,” I stated. “I'll see what I can do, but I can't guarantee the executives will go for this.”

“Oh, come on, Tinker! This kingdom is just full of babies and creatures in need of diapers! This place is practically a diamond mine for them!” Mindset explained.

“True. They'd have to be crazy to pass up an opportunity like this.”

“Well, that's great to hear.” Glitter said with a smile. “Before we do that, though, let's get you set up for the week!” Glitter then called to a unicorn with a yellow and red color, where she proceeded to lift the princess up and carried her. “To your rooms!”

Mindset gave one last wave to all those in the room, which everypony returned, before the two of us followed. “Good to see you again, Circus!”

“Likewise, Mindset. Great to have you back in our kingdom, and we greatly welcome you, Mr. Tinker,” the unicorn returned, nodding to me.

“Thanks.”

“Tinker, this is Circus Rose. She's the adoptive mother of Quick Beam.”

“A pleasure to meet you.” I offered a hoof as we walked, which she returned.

“So, Tinker, are you the type who enjoys the outdoors?”

“Sometimes, yeah. Why?”

“We have a little meeting with the Foal Scouts every week. I was wondering if you'd like to join us.”

“I remember Mind mentioning that. Well, if she's joining you, I'm going along with.”

“Glad to hear it.” She smiled.

“Yay! I can't wait to see you in the uniform!” Glitter shouted, almost loud enough to hurt my eardrums. We arrived at a room that had a sign hanging on it that read “Dr. Mindset Shield, Royal Therapist”. “Your room is right next door, Tinker.”

As Mind opened her door, I got a good look of her office/nursery. The room was a purple color, which I expected with my sister, and Cuddle Bear plushies and foal toys littered the room. On the other side of it was a psychiatry couch with a foal-sized desk, which I assumed was for Mind's job, should anypony need her for that. She wasted no time getting Robu's flower charger set up, which Robu himself perched on and began recharging.

I expected more was in there, but I held off from peering for now as I entered my room. What I saw was a nursery, similar to Mind's, only more gender-neutral. The bed was not a crib, thankfully, but was still pretty foalish, like it was meant for a toddler. There was even a changing table with diapers and some pull-ups. “Uh... I'm not regressing that much.”

“Oh, we know. This room is usually reserved for others around preschool age, but it should still work for you, since you'll be about as young and small,” Circus explained.

“I see, so the diapers aren't for me, then?”

“No, though the regression will shrink your bladder greatly. Most forget that fact and have accidents as they try to adjust, believing they could hold just as much. I recommend at least wearing them tonight after you regress until your body adjusts accordingly, and also so you don't awake with a stain on your bedsheets.”

“Fantastic...” I groaned, noting the plastic bed liner that crinkled loudly upon pressing a hoof on it. It made sense, sure, but it wasn't a fact I was happy with. Still, I adjusted the room to fit my usual style for the vacation; placing my toolbox on the drawing table, which I placed my blueprints on, placing my toiletries in the bathroom, and lastly placing clothes, (which I packed without realizing that they wouldn't fit me when I regress because I didn't know about Mind's agenda beforehoof,) into the dresser. Luckily, the clothes that were already inside would be more fitting for my soon-to-be size. Even better, they weren't completely foalish looking, so I'd be willing to wear them in public. “Okay, all set up.”

“Great, so am I,” Mind said as she entered my room, along with Circus and Princess Glitter.

“Okay, so, if you two are ready, let's not waste any time, and begin the regression.” The princess was all too eager to shrink me to my youth, but Mind was even more excited. The four of us walked down to a hallway that led to a strange fountain, a statue of a mare with her infant foal.

“That's the Fountain of Youth that everypony drinks from,” Mind proceeded to explain.

“Not anymore, I'm afraid. It's mostly just for decoration now that the truth is out. Besides, you two don't want to drink it and regress without your memories,” Glitter added.

“That would be nice,” I commented. “I know Mind here would be immune, but I'm not, so I'd like to not forget who I am.”

“Right, you and many others. That's why Beam and I have been working together to come up with a new regressive concoction that only regresses physically, and lucky for you two, we succeeded.”

“Not quite, but it's close enough.” Another voice I hadn't heard before. I turned to see a young colt, resembling a one-year-old foal. “There is a chance that you might have some mental regression, but the effects are quite minor.”

“Quick Beam!” Mindset immediately hugged the young foal.

“Aye, it's good to see you, lass. How are you?”

“Wonderful. I see you are still being a scientist of nature.”

“But of course. Better ta wear oot as roost oot.”

“Uh... What'd he say?” I didn't understand a single word.

“And just who are you, lad?”

“Oh, Beam, this is my brother, Tinker. He's here to help care for me when I become a foal,” Mind explained.

“Are you now? Well, Imbu da fremd!”

“Huh?” I tilted my head.

“Tinker doesn't really understand Shetland. He's showing hospitality to you,” my sister explained.

“Oh, uh, imoo da, um, friend to you too.” Mind simply slapped a hoof to her face.

“That's not what I said, but I understand your intent. Welcome to Fountonia.”

“Thank you.” I blushed from my awkward attempt. “Anyways, back to business. You said that the water you've been experimenting on has some mental regression still?”

“Ah, yes. It's rare, but we had subjects report some sort of regressive behavior, such as a desire to chew on things they'd normally wouldn't chew, a greater need for attention, quicker to get bored, and so on. However, all cases reported still retaining their memories and being aware of their situation.”

“So it's more like certain parts of their youth are resurfacing? That's interesting,” Mindset stated.

“Which is why I'm telling you this now before you drink. As rare as it is, if you want to continue, just be aware that you may show signs of it.”

“Well, Tinker? What do you say?” She turned to me for an answer.

“Well...” I didn't know what to expect. On the one hoof, I wasn't regressing to baby status, so the chance of me acting foalish was unlikely. On the other hoof, did I really want to chance it for some quality time for my sister, something I could do as an adult? One look into Mind's eyes, however, made me decide. “Okay, I'll do it.”

“Yes!” was all Mindset spoke after that.

“Well, so long as you know what to expect, I can't stop you both.” Quick Beam pulled out two glasses, filled with what I suspected was the youth water we'd be drinking. “These are all set. Prepared them as you were coming.”

I took one look at it. The water looked clear, but had a fizzy-like appearance, almost like sparkling water. “You sure this is safe to drink?”

“Indeed. A hundred percent certain. This water is just that; water. Clean, albeit regressive, water with a bit of carbonation in it.”

“No backing out now, Tinker. You agreed to it,” Mind reminded me.

With one last sigh, I watched as Mindset drank hers, immediately shrinking to a foal. Her clothes and diaper fell off as she continued to get smaller, until she eventually stopped at newborn age. A small giggle left her lips as Circus laid her down on her back for a moment and diapered her in a more fitting size. Hesitant, but not backing out, I took one last look at the glass and drank. I didn't know how much I'd need to drink, but I made sure I didn't regress as far as my sister. Soon enough, I reached the age I had gone for. “Whoa...” I felt weak and lightheaded. The world span for a brief moment before I eventually righted myself. “I don't feel well.”

“Oops, I forgot to mention some nausea is also possible, but no matter. It's just your body adjusting. Why don't you try to rest for a little while. Glitter and I will take care of Mindset in the meantime,” Quick Beam suggested. At that point, I didn't have much choice, as I couldn't keep my eyes open, and I eventually passed out. “Wow, he really is not used to this.”

~*~

I don't remember much of what happened next, but I did recall being on a padded table, (no doubt being diapered as suggested,) and placed in bed. As I continued to sleep, I dreamed of Mind and I playing together in our youth, though she was about three in the dream. It was an old memory I had, of that I was sure of. She was testing out the product of my first creation, a diaper that held more than those bargain bin diapers, straight out of the machine I built. She laughed as I tickled her and she had an accident. Seeing that it worked, I smiled at the success of my creation. She even felt comfortable in them; no clamminess, no fear of leaking, just safe and secure. That was when I got my cutie mark of a six-toothed cog. It was a proud day for me, and I was so excited when I got it. Mindset and Dad were both happy for me. The only thing that would've made it better was-

“I hate her...”

The sudden surprise of hearing another voice caught me off-guard. “Huh?”

“She took her away. She'd still be here if she never existed.” I turned to the source and found, to my surprise, a younger version of me, one that looked as old as I currently was. “She's gone, and it's all her fault.” I couldn't tell, but something about what he, (or rather I,) said sounded so... Familiar. “I never want to see her again!”

“Never see who again?”

A pause before, “That mistake of a unicorn.” His eyes... My eyes... They were filled with so much hate, and hurt. They narrowed on the image from earlier, focused on the blue-colored foal that smiled at my success.

“Mindset?”

“You'll see. Once she's gone, the world will be a better place.”

“Whoa, hold on now, that's not how you-” But before I could finish, a light blinded me. “Ah!” I didn't know what was happening, but I started feeling such pain. Not physical pain, but emotional, as if waves of sadness and rage flooded every portion of my mind. It was too much! I collapsed within the dream.

The next thing I knew...

Something within me began to change.