Tags: [Alternative Universe] [Comedy] [Slice of Life]

Characters: [Amethyst Star] [Derpy] [Dinky]

Written By: Foal Star

Note: Takes place within Foal Star's age regression AU between the events of "Royal Foal Wedding" and "Twilight Sparkle Lost in Time", also an unofficial sequel of sorts to "Big Muffin, Little Muffin" by SuperPinkBrony12 and "The Stork & the Mail Mare" by Yosh E-O.

Amethyst Star hadn't suspected or expected anything to be out of the ordinary when she was "adopted" more or less by the Hooves family: Including the constantly absent Time Turner and the loving, well meaning, but clumsy Derpy. After everything else that had been going on in Equestria ever since this thing about a "foal pandemic" had first popped up, nothing really surprised the unicorn anymore.

That is, until her newly adoptive mother approached her with a most unusual request soon after Amethyst Star had settled into the Hooves household. To put it simply: Derpy took Amethyst Star aside and asked her to wear a diaper.

Amethyst immediately tried to shoot down the idea. "No." She told Derpy in no uncertain terms.

"Come on, Amethyst," Derpy pleaded with the best smile and puppy dog eyes look she could muster up. "It's not for my sake, it's for Dinky's."

Amethyst was still not onboard with the idea in the slightest. "The answer is still no, Derpy."

Derpy was quick to correct. "Ah ah ah, you have to call me Mom now."

"Fine, Mom," Amethyst grumbled. "I'm still not doing it. I have no idea how me putting on a diaper at all benefits Dinky. I'm older than her, and I'm sure she knows it."

"But don't you see," The wall eyed pegasus mare pleaded. "That's exactly why we need to do this," And she confessed. "Look, the thing is, I was working on Dinky's potty training. Really, I was. And then I got turned into a foal again because of some magic muffins, and then there was the entire royal wedding fiasco, and then my husband went away with Princess Twilight. And so everything kind of got thrown out of whack, Dinky's potty training included," She blushed. "But I remembered something from before I met your father, and before he brought me to this timeline."

The light purple coated unicorn mare struggled to resist the urge to roll her eyes. All of that sounded way too outlandish to be true, even for somepony like Derpy who was known to have the most eccentric family of anypony anywhere in Equestria. "And how does that relate to forcing me to wear a diaper?"

Derpy struggled not to put a hoof to her face, she couldn't believe her adoptive daughter was being so needlessly dense right now. "Well, in the timeline I originally was from and where I originally had Dinky, and keep in mind this was before I met your father and found out he'd erased my memories of us meeting for my own protection," She coughed into a hoof, quickly wanting to change the subject. "A-anyway, in that timeline, I was raising Dinky all on my own. Well, not entirely alone. I had help from someone called Nixi. She was really strange, but she was really helpful to me, especially when I was potty training Dinky for the first time so that she could go to school."

"Uh-huh." Amethyst Star slowly nodded, still sounding rather skeptical of the whole premise.

The wall eyed mare continued to explain. "Well, long story short, Nixi had me er… demonstrate what to do so that Dinky would get the right idea. Except I kind of ended up doing the wrong thing… o-on purpose, mind you. A-and what matters is that it worked. But after I got turned into a foal, I think if I was the one to do it this time, Dinky wouldn't understand. Turns out me being a foal on top of everything else that was happening threw the whole timeline out of whack, and undid some things: Dinky's potty training being one of them."

"So, now you want me to do what you did for her last time, is that it?" The unicorn mare concluded, sounding anything but pleased with the idea.

Derpy blushed. "Just this one time. You won't have to actually use it like I did… unless you want, of course. Remember, we're doing this for Dinky's sake. We just need to jog her memory, that's all. So come on, please?" She began to plead.

Amethyst groaned and moaned under her breath. Much as she wanted to refuse the outlandish idea, something told her that Derpy was going to just keep on begging and pleading with her until she accepted. So she reluctantly agreed. "Fine. If it's really to help Dinky, I suppose I'll do it. But it's only this one time. And if it doesn't work, it doesn't work, I'm not staying in diapers until she gets out of them."

The grey coated pegasus pony smiled and clapped her hooves. "Excellent! See how easy that was when you just went along with what I wanted to do?" She giggled as she then instructed her newly adoptive daughter to lay down. "Now just relax, we'll get this diaper on you in no time flat. And then we can go right to staging our little demonstration for Dinky. Wait 'til my husband comes home and sees how well I managed at fixing up everything. He's not the only one who's good at fixing things."

Amethyst, meanwhile, was muttering to herself. "What did I do to deserve this?"

Soon, Amethyst Star was all padded up. She absolutely hated the sensation of having a diaper hugging her rear, and wanted nothing more than rip it right off her haunches. But she convinced herself not to do so. This was for a good cause after all (supposedly).

"Alright, Amethyst, we're all set," Derpy cooed. "Now just stay there and do exactly what I tell you to do: Got it?" When she received a nod, she then gave a whistle and called out to her other daughter. "Oh yoo hoo, my little muffin. Can you come here, please? Mommy has something very important she wants to show you."

Dinky soon came toddling over with a bright smile on her face, her diaper crinkling audibly as she did so. "What is it, Mommy? Whaddya wanna show me?"

"Something that everypony your age has to learn," Derpy explained. "In fact, you already learned it once before. But then you forgot it. And I wanna help you relearn it," She cleared her throat, gesturing to Amethyst Star. "Do you see what your big sister is wearing?"

Dinky nodded. "Uh-huh. She's wearing a diaper, just like me," Then she blinked. "But why? I thought she was more like you and Daddy and didn't need to wear diapers?"

The wall eyed mare nodded back. "You're right, Dinky, she doesn't. In fact, you don't need to wear them anymore either. And your big sister is going to show you what you're supposed to do instead whenever you have to go. Let's all go into the bathroom so you can see," And she lead both padded unicorns into the bathroom, Dinky following along willingly but Amethyst doing so much more reluctantly. Once all three were within the bathroom, Derpy went on explaining. "Now then, when your body starts showing signs that you need to go, you have to come here to the bathroom. Once you do, the first thing we do is take off your diaper." And as she spoke she turned to Amethyst Star.

Sighing deeply, Amethyst allowed Derpy to pull down her diaper all the way, treating her as if she were really just a big toddler. The entire experience was humiliating and embarrassing.

Derpy continued. "Then you just sit down on the potty, relax, and let it all go. Make sure your diaper is pulled down before you do that, though. Otherwise you'll… well, you get the idea."

Amethyst, meanwhile, sat down on the toilet with a frown on her face. She tried to tell herself it was for a good cause, but that didn't really make her feel better. What was worse was that Derpy made her sit there for what felt like forever, clearly hoping that the elder unicorn would do something. After sitting there for several minutes, Amethyst reluctantly decided to cooperate by opening her floodgates, allowing for a steady stream to trickle into the toilet bowl.

"Great job, Amethyst!" The wall eyed pegasus proclaimed with exaggerated praise, before turning to Dinky. "See how easy it all is, my little muffin?"

Dinky nodded, fascinated by the whole experience. "Uh-huh, Mommy. It looks like fun! I wanna try! I wanna try!"

"Well, first we need to wait for your big sister to finish," Derpy instructed. "Then, after I help her wipe and flush, you can try it too."

"Use the big potty?" Dinky questioned.

"Huh…" Derpy blinked, before realizing a detail she had overlooked in her eagerness to re-train Dinky. "O-oh, you can try using it if you really want to, I guess. I'll just… have to get a little something for you since you're a little small. But I'm sure I have that something around here somewhere," She then turned back to the unicorn mare sitting on the toilet. "So, Amethyst, are you all done going potty like a big filly?"

Amethyst managed to force out. "... Yes, I believe I am."

"Good!" Derpy cooed as she helped the elder unicorn to stand. "Now we just wipe up with some toilet paper," She pulled some toilet paper off a rack and gave it to Amethyst. "Make sure to wipe from front to back," Once she saw the used rolls be discarded into the toilet bowl, she then declared. "And now we flush. Go ahead, you know what to do."

Amethyst pressed the lever down to activate the flush cycle, then trotted away to wash her hooves as she was convinced that she had done all that she needed to do. With any luck, Dinky's memory had been refreshed, and the child would no need further assistance in learning how to use a toilet like all big ponies did.