[Soiling, Humiliation]

“Hyah!”

A vigorous cry echoed out through the plains of Mondstadt, as a young blonde girl swung her blade through one of the native Monsters that had been hounding her ever since she arrived in this strange world…

She could still remember the shock that flooded her when she saw that strange girl. The one that had separated her and her brother, and simultaneously stripped away the power that she had. She couldn’t fly anymore. As much as she’d like to.

“Hey! The monsters aren’t done yet!” An energetic voice cried out, as the blonde girl quickly spun around to face the other enemies that tried to creep up on her.

The girl, Lumine, was starting to sweat a little. Sure, she wasn’t shabby with a sword, but that didn’t mean she could last long in a fight. Especially not with all of her original power stripped from her.

“Won’t they stop?!” She shouted as she parried a blow from one of the monsters’ clubs, slamming her body into it to knock it away, giving her some breathing room.

Only for her stomach to start cramping, her eyes growing blurry. What was this feeling inside her..? Why was it so painful? And how could she stop it..?

“H-Hey!” The energetic voice from earlier rang out as the owner, an adorably small white-haired fairy, quickly started circling the blonde girl. “Snap out of it! If you don’t fight back, they’re-”

Lumine didn’t need to hear it. She could handle it, despite the pain in her tummy. She grit her teeth as the last monster approached her with the same wild intent to smash her silly, only for her to deliver a stab straight through its mask. It soon dissolved into mere sparks, giving her a moment to breathe…

And a moment to gasp as she felt something slithering its way out of her butt, making her quickly blush as she realized what it was. That made all of the pain inside her make all too much sense.

She was messing herself. Filling her panties with nothing but pure waste. A feeling that she thought she wouldn’t experience ever again, but since she lost her powers… Of course this would come with it. How couldn’t she have seen this coming..?

“Phew! You’re safe!” The white-haired fairy grinned a little, patting her blonde friend on the head. “Tell you what, I thought you were actually in danger! Good thing you’re not, I would’ve hated to see you go so soon!”

Lumine bit into her lip as she listened to her fairy companion’s words. They were supposed to be comforting and relieving, but if anything they just made the pain and agony of what was happening all the more terrible. “P-Paimon, c-could you…”

The Fairy, Paimon, blinked a couple of times as she noticed the look of agony on her buddy’s face. “Eh? What’s the matter? You beat the monsters, there’s nothing left!” She chimed, puffing out her chest a little. “Why, there’s no reason to be pained or anything! Just take a moment to relax, then we’ll be on the road to find your brother aga-”

“C-Can’t stop it..!” The young blonde cried out as she closed her eyes, the pain in her tummy growing as the excrement stuck inside her bowels just kept on pouring out. At first, she could handle it and she wouldn’t stink as much so the fairy wouldn’t pick up on what was wrong. But now that all the waste that she had been keeping inside her started pouring out, how was she supposed to cope..?

Paimon caught a whiff of the smell, her cheeks turning green as she realized what was going on. “Wait, wait wait wait wait, are you pooping your panties? You? The girl who keeps calling me emergency rations because I’m small and compact, making a mess of yourself?” She asked, her expression slowly but surely turning into a bit of a mean grin. Did she have the chance to turn the tables for once..?

“S-Stop it, Paimon…” Lumine muttered, her panties sagging as the mess kept pouring in. It was gross. It was humiliating. It was something that she never hoped to go through ever again. And yet here she was. Filling her panties like she couldn’t control herself. Who could? Where she came from, there was no such things as toilets, and thus the magic kept everything in control…

But now, with the panties struggling to keep it all held in… What was she supposed to do? All her instincts told her was to try and keep it from squeezing its way out of her butt, but that didn’t help. She just couldn’t.

“Gee, Lumine! Here I thought you were big and strong and smart with how much you tease me, but I guess you’re just a little pants-pooping baby!” Paimon giggled, hovering down towards the mess while gagging a little. “O-Okay, maybe not little, sheesh. How much do you even have in there?”

Lumine didn’t want to answer. Not with how badly all of this felt. She just wanted it to be over, as she fell onto her knees and tried not to focus on it. It felt awful. The stench, the texture, everything.

“Hey…” The fairy started frowning a little as she noticed how absolutely terrible the blonde girl looked, floating up towards her face as she gently wiped away the tears that were starting to pour down her face. “It’s okay. It’s just something that happens. Okay?”

The blonde girl slowly sniffled as she looked straight at Paimon, her tears still rolling down despite her best efforts. “B-But… B-But I thought I couldn’t do this anymore. I didn’t think I’d ever make a mess again…”

“...Ever?” The fairy asked, tilting her head slightly. “But people gotta poop sometime, right? Are you saying that you never pooped? Ever?” The white-haired fairy honestly had trouble believing that. Like, how could somebody just not poop? Did they have a trick or something?

Lumine slowly took a deep breath, as she explained it piece by piece to the fairy she called a companion. Hoping that her sympathy would continue. Hoping that she would help her.

“Okay, so… You couldn’t poop because of magic, and that was a good thing, and then that bad lady you talked about took that away, and you never thought that it’d stop you from holding it in?” Paimon recanted everything she heard, as a bit of smoke started pouring out of her ears. “That doesn’t make any sense…”

The blonde girl wiped a couple of her tears away, shaking her head. “It’s the truth, Paimon. Nothing but the truth. And now I’m stuck without… without…” She muttered, realizing that she’d have to live with a set of bowels that were utterly unpredictable…

“...Y’knoooow.” The white-haired fairy started trailing off, as she floated down towards those stinky panties and pulled them off, despite how sick they made her feel. “There’s something that humans use in case of emergencies like this.”

Lumine’s eyes brightened as she heard that, looking down at the fairy while lifting her leg slightly to allow those filthy undies to get bunched up. “You… You know a way? A way that I can stop worrying about my-”

“I didn’t say that you’d stop pooping.” Paimon quickly shot her down, before smiling a bit after. “Just a way to not make it as embarrassing.” The helpful fairy chimed, patting the girl’s dirty butt to bring a bit of emphasis to it.

The blonde girl bit into her lip slightly, huffing. “I don’t want to poop, Paimon.” She muttered. Almost like a child that didn’t get her way. Such an uncompromising position…

“You wanna keep filling your panties, or do you want something that can help with it?” The white-haired fairy laid down the ultimatum, grinning a little. “Honestly, I’d love to see you fill them more. Maybe you’ll start liking it after a while, you big baby.”

Lumine blushed a bit more as she considered her options. On one hand, she could keep making a mess of herself. On the other, she could endure whatever the fairy had planned, and then she would hopefully rein in her bowels after some amount of time…

“F-Fine. W-What do you have planned?” The blonde girl muttered. She didn’t like being on the backfoot. Especially when it concerned this little gremlin of a fairy. But if it meant she could train herself to not make a mess, then.

Paimon gave her a thumbs up, before grinning a little. “You’re going to love it. Trust me!” She chimed, hiding all of her plans behind that bright smile.

Of course, she didn’t mention that the solution would be for the blonde to wear something meant for infants that didn’t have the chance to develop control in any way shape or form, but that was part of the fun of it. Besides, she’d be cute in diapers.

Thus, the two continued their adventure. With one short stop for new undergarments planned, and future embarrassment in store for the brotherless girl...