[Soiling, ABDL, Diapers]

After the Fifth Holy Grail War came and went, tearing through Fuyuki yet again, life was slowly but surely turning back to normal. Somehow, someway, the Servants that had been a part of that war had managed to stick around. Integrating into society as a whole. And the people that once fought one another to take the lives for the sake of the wish-granting trinket, were now joining hands and staying merry…

But where one problem ended, another one started. A smaller problem, since it concerned nobody except for a certain purple-haired Servant. Rider, alias Medusa, had been graced with the worst reward of all. A visit from her older sisters, who she had thought to devoured in the years where she was nothing more than a Monster. And yet, there they were, in the flesh. Still as mockingly terrible as ever…

Not even a few minutes after meeting them once again, and they started biting into her with their terrible remarks. Insulting her body, insulting her mind, insulting everything about her and downplaying her better traits. Because that was what they did, thinking that it was how to deal with such a malformed sibling.

Medusa couldn’t take it. She retreated into her room inside her Master’s home, trying to sleep through the days that came and went. She didn’t care about appearance. She didn’t care that her strength, which she had shown plenty of during the War, was reduced to nothing more than whimpers and whines as she cuddled up in her safe space…

Just the thought of them made her sick to her stomach. In fact, she could remember how they bullied her when she was even younger. Those memories that she had tried her best to block off. Like when they forced her to cry so hard that she eventually soiled herself, laughing and mocking her for how much of a baby she was.

“I-I’m not… I’m not a baby…” The purple-haired Servant, whose cheeks were currently slathered in tears thanks to the memories of the past, sniffled and sobbed as she felt her stomach cramping up. The more she thought about the past, the more it came back to haunt her. Even now, when she had attained perfect potty training compared to when she was forced to soil herself…

She wrapped her arms around her sides, trying to hold back the flow. But her mind was in too great of a shock to keep it together. She could hear those piercing voices stab into her heart, and she just had to close her eyes for comfort. Even as she felt something sliding out of her. Something foul. Something infantile. Something that she had hoped to never do ever again.

Medusa, the petrifying Monster that had claimed the lives of many, was sobbing like an overgrown child as her pants started to bulge outward. Her poor denim jeans, those that had been specifically picked out for her by her Master, were growing a bit darker around her crack. Her panties weren’t enough to stop the flow. They just kept it from pushing even further out…

“I’m not a baby, I’m not, I’m not..!” She cried out, as if she was throwing a tantrum. the poor woman was regressing thanks to her trauma, little by little pushing more of her adulthood out. She couldn’t stop. Not when her mind was filled with those two girls’ eternal mockery…

The smell of her own poopy reached up to her nose, and she grimaced. The tears kept on rolling down. She knew better than to be repulsed by something she couldn’t control. She knew better than to crumple under pressure like this. But here she was. A mighty Monster, slayer of heroes, reduced to nothing more than a broken woman trying to keep it all together.

“Rider? Are you okay?” And as if her life couldn’t get any worse, she heard the sound of a gentle voice echo through the door to her room. “I was wondering if you’d like to come down and eat, Senpai’s cooking.” The voice continued, not yet realizing what had gone wrong…

Medusa could feel her heart sinking. She was going to have to face her Master like this. With a big bulge of poop in the back of her pants. “S-Sakura, don’t come inside. Please.” She mustered up a protesting whine, carefully lifting herself up and wincing as she sat her plump posterior down on the poop in her packed-full panties…

Despite what her Servant wanted, Matou Sakura entered her room. Because she knew that she couldn’t let her stay in here, not when she was acting so dangerously out of character. “Rider. You don’t need to stay in here all by yourself. Tell me what’s wrong, and I’ll do what I can to help you.” The violet-haired girl said with a reassuring smile on her face. Even though she could smell the waste that had left the proud woman’s butt, she didn’t seem to be phased at all…

“Sakura…” The purple-haired Servant gasped, as she slowly but surely stood up to face the girl that she served. “You’re…” She paused, before closing her eyes and accepting that she couldn’t talk her way out of this. Using her Mystic Eyes wasn’t an option either. “...Promise me that you won’t mock me for this. Please.”

Her Master carefully reached onto her cheek and rubbed away at it, kneading with her thumb as she giggled. “Rider, I’d never mock you. You’ve done everything in your power to save me before, why would I treat you with anything but love? You just have to tell me what made you become like this, and then everything will be alright.”

Medusa slowly nodded as she cleared her throat. The words didn’t want to leave, but she had to force them out somehow. “...I… I met my sisters. Stheno and Euryale. And they laughed at me. Just like so many years ago.” The incontinent woman muttered, her cheeks flushing a little red as her poor butt was forced to push a little more filth out. “...The memories have left me unable to control my bowels. Just like they’ve always said, I’m nothing more than a baby…”

Sakura nodded as she listened along, before putting a hand on the older woman’s shoulders. “Even if you may be a baby, Rider, you’d be my baby. As long as you’re by my side, whether you’re an adult or a little girl, I’ll do what I can to make you feel safe. You can trust that.” She sounded so reassuring, a far cry from the girl she had once been.

To think that their relationship could be turned around this dramatically. During the war, her Master was the one that needed support from her. And now, with Rider being the one in trouble, she was the one that needed all the support that she could get. Even from a girl that she had helped so many times before.

“...I can’t thank you enough, Master. But… W-What do you mean by your baby, exactly?” Medusa spoke up, feeling that there was some sort of ulterior meaning to the concept of being her Master’s baby. Especially considering the kind of ‘tortures’ that her Master knew of…

Sakura started smiling. Way too eerily. “Well, I was wondering why your pants were turning up a little dirty over the last few days, and I decided to be proactive.” She chimed as she stepped back towards the doorway, only to pick up a rather infantile looking package. Something that was perfect considering the latest revelation.

“You… Master, I’m…” The purple-haired woman with her pants still full of her latest mess tried to protest, but she knew that she couldn’t say anything. She had just put her trust in her, it would be awful to tell her to stop. “Just don’t rub it in, please.”

The violet-haired girl giggled as she tore the package open, revealing a set of adorable diapers. Ones with Unicorns dotting the plushest parts of the garment. “Would you be a dear and strip down, Rider? It’d be best if we get you started on these as fast as possible. Just in case you have an accident while we go out.”

“G-Go out?” Medusa’s cheeks flushed bright red. Yes, of course they’d go out. But she hadn’t thought about the fact that she’d be seen with one of those things around her waist. If her sisters saw her like that, she might actually die for real this time. But at the same time, if she didn’t wear one, the trauma would just come back and haunt her even more. She was stuck between a rock and a hard place.

Sakura didn’t need to say anything else. She just patted the ground as she sat down, waiting for her Servant to strip of her own accord. Once she was disrobed, the meat of their ‘fun’ would begin, and then they could spend lots of time together. Not as Master and Servant, but as something more intimate. Something that would let her heal that trauma she had been saddled with.

Rider hesitated as she reached towards her sweater, only to sigh and accept it. She pulled it off with surprising ease, letting it fall to the ground as she shivered. After that came her denim jeans, which slid off and revealed the mess that was in her panties in the process. And what a mess it was, considering the smell and the size being nearly enough to fill out the crack between her buttocks in its entirety…

The violet-haired girl brought forth a couple of supplies that she had snuck into the package, just in case this stuff had to happen. Baby powder and wipes aplenty, the latter of which was especially important considering just how terribly stinky her Servant had gotten. “Turn around, Rider. I’ll get you clean before your change.”

Medusa did as she was asked, her body shivering as she felt those wet towels rub up against her body. It was a delicate touch, not unlike the few times where her sisters had been kind to her. But unlike those times, she was with somebody who she trusted completely. Somebody who wouldn’t hurt her, no matter what.

Sakura’s movements were gentle, yet thorough. Any spot that was dirty got a second pass over to ensure that the brown stuff that had stuck to her body was wiped off properly, then a third to keep that surface spotless. And when it came to her Servant’s most precious areas, the ones that could potentially trigger even worse memories than the ones about her sister… She was delicate enough to wipe away the dirty parts with precision, just to lessen the chance of an episode.

Once she was nicely cleaned up, it was time to apply that powder. A generous smattering onto the important areas, just to make sure that she didn’t get a rash when it mattered, and a thorough rubbing that made sure to not hit the most sensitive areas, and she was ready for the diaper to come on…

Rider laid down, her heart beating through her chest. She could feel it pounding, aching as she lifted her legs into the air. If it had been anybody else that was changing her, she wouldn’t be feeling like this. She’d be terrified or embarrassed, but when she looked down at the violet-haired girl she called a Master… She couldn’t be happier.

Sakura went through the motions, something she was strangely familiar with. Under the baby’s bottom, through the legs, and snap the wings shut to keep it nice and snug. She even gave it a couple of taps on the front to ensure that she wasn’t going to end up leaking, before giggling. “There we are. You did great, Baby Rider.”

The nickname was embarrassing, but it was something she preferred to humiliation at the hands of her sister. “Thanks, Master…” She quietly muttered as she sat back up, sighing. Hopefully she could carry on her life as normal from this point onward…

Only for her Master’s lips to meet her cheek, and a whisper to reach into her ear. A whisper that would change their dynamic for the foreseeable future. And give her the comfort she so desperately desired.

“Call me Mommy from now on. Okay, Baby Rider?”