Author's Notes:

I couldn't resist doing a chapter about Sunset, and I think any last traces of doubt and shame about my fetish fantasies are gone.

Of course, this will be as much pure fetish fuel as the other chapters!

In the Equestria Girls world, Rainbow Dash and Applejack were away on a big trip to another city for a sports competition. Twilight Sparkle, Fluttershy, and Pinkie Pie were with them, Twilight wanting to go to a museum, Fluttershy wanting to go to a petting zoo, and Pinkie Pie wanting to throw a big party for Rainbow Dash and Applejack once their competitions were over.

Sunset Shimmer and Rarity stayed behind, as Rarity had a deadline to finish, which she had on the second day the others were gone for, and Sunset had a dentist appointment on the same day.

They didn't mind too terribly, though, and on the night of the second day, when all they needed to do was done, they had a sleepover at Rarity's house.

After a pillow fight, it came time for Truth or Dare.

"Rarity, truth or dare?"

"Truth."

"What's your deepest, darkest, secret?"

"Can you ask me something else?"

"You can't change the question."

"I really don't want to tell anyone this..."

"You can give me ANY dare you want after this. Even if it's pulling my pants down and spanking me 50 times!" Sunset blushed lightly, for she wanted Rarity to do this.

"ANY dare?"

"You got it."

"Well... Two months ago, the sirens tied me up, and gave me a spanking. And they made me fart a lot. And they made me wet myself and soil myself. Only Applejack and Pinkie Pie found out, and Applejack punished the sirens, but... I've only ever told Applejack this, but a part of me enjoyed all of it. Too much, for someone as ladylike as me." She was blushing beet red now. "And, I've been asking her to get fart powder for me often, because I... I really love to fart. And, some nights, I stand in the shower and pee myself. Twice I even got Applejack to do the same thing to me that the sirens did. I think I have a fetish for all that."

"Wow," said Sunset. "I never would have guessed."

"So, there you have it. I hope you won't think any differently of me..."

"Not at all," said Sunset. "I have fetishes too. Everyone does. And a deal's a deal. Give me any dare you can think of, no matter how extreme. Unless it's something like turning into a demon and attacking people again."

"Well..." A devious grin spread across Rarity's face. "Sunset, truth or dare?"

"Dare, of course."

"I dare you to let me tie you up and do whatever I want to you for as long as I want!"

Sunset felt a little nervous at this, but she wasn't about to back out of her deal with Rarity.

They walked into the basement, where Rarity set up an old mattress she rarely used anymore, and had Sunset get on it. Sunset was sure, so she wouldn't have to sleep on the floor. Rarity tied both of Sunset's feet together, and her hands behind her back.

Rarity had gotten a box full of cans of Coca Cola for the sleepover, because she knew it was Sunset's favorite drink. Sunset had already drank three cans tonight, and Sunset had her drink two more.

This isn't so bad. She's giving me my favorite drink.

"Raise your rear end in the air," said Rarity.

Sunset did as she was told, her heart pounding. Was Rarity really about to do what she thought she was?

SLAP!

Sunset let out a squeal of pleasure as Rarity slapped her butt. Her pajama pants were still up, but Sunset loved it either way. This was her biggest fetish.

Rarity swatted Sunset's rear a total of 20 times.

"Oh, your poor bottom must be in so much pain," said Rarity once she was finished.

Sunset's butt did hurt, but she didn't mind, having greatly enjoyed the spanking.

"Would you like a butt massage?" said Rarity, who couldn't stop staring at Sunset's butt and how cute it looked in her pajama pants. Sunset had the biggest and cutest butt of any of her friends, including Rarity herself.

"Sure," said Sunset. "If that's what you want to do, I mean." She blushed a little.

Rarity rubbed Sunset's butt. It felt so soft against her hands, and she liked the feel of the fabric of her pajamas as well. Sunset was enjoying this as much as Rarity, and couldn't hold in her sigh of satisfaction.

But, after about five minutes, she couldn't hold in something else either.

FFFFFRRRRRRRT!

"Ooh, Sunny, what did you eat?" said Rarity as she took a whiff of the fart.

Sunset blushed. "I'm so sorry Rarity. I didn't mean to..."

"It's not your fault. It's mine for putting fart powder in your drink. You are going to get really gassy."

So, Rarity was going to make her fart? She sure kept up her ladylike facade well when she was with the others. It was still a little embarrassing.

PPPPPPPPPPFFFFFFFTTT!

Sunset let out another loud fart for about 9 seconds. Rarity didn't stop rubbing Sunset's tush, and inhaled deeply.

"Let me know if you get hungry or thirsty," said Rarity.

Rarity had the heat on in the basement, so Sunset was starting to sweat. After half an hour of farting, Sunset told Rarity she was thirsty, so Rarity gave her three cans of coke - each containing fart powder. In-between farts Rarity would sniff Sunset's butt. Sunset thought this was a little weird, but mostly coming from Rarity, and she secretly liked it.

An hour into the dare, Sunset felt something else inside her.

"Rarity... When are you going to untie me?"

"The night before the other girls get back."

"But that's four days from now! I can't hold it that long!"

"Hold what?" Rarity was feeling a little aroused.

"I have to go to the bathroom. I drank what, eight cans of pop?"

BBBBRRRRRRT!

"Just hold it," said Rarity. "Or go in your pajama pants."

"I can't! It would be way too embarrassing." She let out a quiet, airy fart for about 14 seconds, which Rarity heard.

"The dare was I could do anything I wanted to you for as long as I said."

"Right," said Sunset, who was regretting asking Rarity's deepest secret now and knew where this was going. "I'll just hold it."

"For four days? I don't think so. Things are going to get wet before this is over."

Sunset fidgeted, struggling against her bonds, but Rarity had tied them tight and she couldn't get out of them on her own. When Sunset's farting began to decrease, Rarity gave her three more cans of coke, which she reluctantly accepted.

Another hour later she really needed to go, and in her current position she couldn't hold herself or even cross her legs. It didn't help that Rarity kept slapping her behind, causing jolts of pain and excitement, and then rubbing it, causing relaxation, both of which nearly made her lose control.

Another half hour later, when Rarity slapped Sunset's rear, she accidentally leaked a little into her red panties, and let out a whimper. Then Rarity gave Sunset another butt massage, causing her to leak for about five seconds, dampening the crotch of her pajama pants.

"I don't think I can hold it," said Sunset. "I have to pee REALLY badly!"

"Just let it all out," said Rarity. "Relax. Think of how much you're enjoying me rubbing your tushie."

Sunset couldn't deny, while most of her concentration was on her very full bladder, part of her was still enjoying Rarity's hands caressing her rear. She started to relax a little, leaking for seven seconds this time and forming a dark spot on her crotch, while at the same time farting loudly.

"You don't want me to pee all over the mattress, do you?" said Sunset.

"That's what I got it for!" said Rarity. "Nowadays I only use this mattress when Pinkie comes over. Sometimes she drinks too much pop and cider, and wets the bed." She slapped Sunset's butt lightly, causing Sunset to squeal and let another spurt of pee leak into her underwear.

Ten minutes later, Sunset fidgeted more, and leaked for four seconds on a loud 15-second fart. Her leaks quickly became more frequent, as her bladder was quivering and she was losing control. She knew she was about to burst, and that Rarity wouldn't untie her.

Then, came a leak Sunset couldn't stop. Five seconds. Ten. Fifteen. Twenty. She tried as hard as she could to stop her stream, but she couldn't. Sunset was peeing herself all the way. She blushed with embarrassment as she soaked the crotch and legs of her purple pajama pants.

Despite her humiliation, Sunset couldn't help but sigh in relief. It did feel nice to let go after holding it in so long, and she had to admit to herself, she liked the warm feeling of the pee soaking her crotch and running down her legs, as well as some naughty pleasure from doing something like this.

She peed for about a minute and 15 seconds, farting twice in the middle of it, and enjoyed the feeling of relief when it was done. Her pajama pants were wet, and so was a large section of the mattress.

Rarity got Sunset into a sitting position so she was sitting in her puddle of pee. She made Sunset drink the last four cans of coke, saying she'd get some tomorrow.

Sunset let out several wet farts as she sat in her wet pajamas for another two hours, in the middle of which Rarity gave her three glasses of water. After the two hours, Sunset had to pee really badly again. She'd hate to admit it, but she had really enjoyed wetting herself once. She knew Rarity would force her to do it again, but she didn't want her to know how much she wanted to.

"I have to go pee," said Sunset. "Again."

"Well, what are you waiting for?" said Rarity.

Sunset let out a fake sigh, and began peeing like a race horse. She blushed lightly but gave a deep, satisfied sigh as she felt the warm wetness re-wet the crotch of her pants, further soaking her butt which had been damp from sitting on the wet section of mattress before.

Once she was done peeing, she let out a loud fart, and giggled.

"You're really enjoying this aren't you," said Rarity.

Sunset blushed more. Rarity simply got her back facedown and on her knees, slapped her pee-soaked butt 15 times - though a little more lightly than before - and then rubbed it, loving every time Sunset accidentally farted on her, and Sunset couldn't hide how much she loved it.

Once Rarity was done, she gave Sunset five glasses of water, and set her on her side.

"I'm going to bed now. Good night, Sunny."

"Good night Rarity," said Sunset.

...

Sunset woke up. She initially struggled against the ropes, before remembering the position she was currently in. Her pants and mattress were still damp. She needed to pee more than her usual morning pee. So, she sat up and let it all out in her pants, sighing of relief and giggling. She could see why Rarity loved this so much. It was also arousing for her, and she might have discovered a new fetish.

"Good morning, Sunny," said Rarity as she walked into the room, wearing her usual purple skirt.

Sunset farted loudly. "Good morning, Rares."

Rarity gave Sunset a bowl of her favorite cereal for breakfast. She gave her three glasses of water, and left to get some coke.

Sunset released a flurry of wet farts while Rarity was gone, giggling with each fart.

When Rarity returned, she went back to slapping and rubbing Sunset's butt, while giving her cans of coke, Sprite, or root beer, which she had now gotten a lot of.

At noon, by which time Sunset had peed again, Rarity gave Sunset some hot dogs and a big plate of beans. Sunset liked these foods but rarely ate them around her friends because it made her gassy. But, she felt no shame of farting in front of Rarity, and thought it was fun.

By now her pajama pants smelled of pee and farts, with a bit of sweat. Her panties, twice as much. But, Rarity seemed to like it.

At about 3:00, Sunset said "I have to pee, REAL bad!" Intending to hold it as long as she could so she could enjoy the wetting more.

"So do I," said Rarity. She stood above Sunset so that she was between her legs, and hiked up her skirt so that Sunset could see her purple panties.

"Rarity, what are you-"

She paused as a thick stream of pee cascaded on her, soaking what parts of her were still dry within seconds, while Rarity sighed in relief. Sunset couldn't believe it - Rarity was peeing on her. Through her panties. She had heard of this somewhere before. This was called a golden shower, and she liked it.

A combination of excitement and the warm wetness of the shower caused Sunset to start peeing as hard as she could. She had never known this could be so fun.

Once both girls finished wetting themselves, Rarity spanked Sunset 30 times, and massaged her tush to make the pain go away. Rarity stayed in her wet panties the entire day.

For supper, Rarity gave Sunset a big plate of chili and some hot dogs. With some fart powder sprinkled on.

Sunset peed a few more times that day, and farted more times than she or Rarity could count, but she was greatly enjoying this.

...

On Day 3, Sunset woke up to find her pants soaking wet, instead of the dampness from yesterday morning. She had peed in her sleep. She figured this was because of her current state and it would go away once she returned to her normal lifestyle. If anything it made her more aroused.

"How's Sunny doing today?" said Rarity.

"I wet the bed," said Sunset without shame.

"Ooh, time for 20 spankings!" said Rarity, and Sunset squealed in excitement, peeing a little more.

Today went the same as usual, except, after peeing on her again through her same pair of underwear, Rarity gave Sunset some prunes, along with some prune juice with fart powder in it. This made Sunset a little nervous. The last time she had eaten prunes, it had quickly made her need to poop so badly she had to do it behind a tree. No one had seen her do her business but they had heard it, and once she was done, Pinkie had checked behind the tree and incessantly described her pile of shit, which had been hyperscat - a lot of small, very soft and wet particles had come out at once. It was so wet that Sunset had needed to change her underwear, even her shorts, when she got home.

Only ten minutes in, Sunset let out a boisterous fart, and could feel her underwear get dirty. Rarity giggled at the sight of a brown stain at the back of Sunset's pants, but she hadn't quite messed herself yet.

"Rarity... I need to go... BAD! And I think you know what I have to do this time."

"That doesn't change a thing. Go in your pants, like I did."

"I don't think this will be as fun as peeing myself."

"It might be. And you have to do whatever I say until the night after tomorrow."

Sunset held it as long as she could, in her facedown position, sweating profusely from the effort and letting out several farts that were wetter and smellier than before, a few of which were sharts.

Until she could hold it no longer.

PPPPPBBBBBBLLLLLLLLLRRRRRRRRRRT!

Sunset noisily filled her already wet and smelly pajama pants with a big, wet, brown mess. A lot came out at once, and she soiled herself for eight seconds. Rarity let out a squeal of excitement as she saw a brown bulge appear on Sunset's butt. Sunset cringed as she felt her mess leak through her heavily soiled underwear and down her legs, and a very unpleasant smell reached her nose.

Rarity set Sunset in a sitting position so she could feel her mess squish beneath her rear. She wiggled around a bit, before realizing she enjoyed the sensation, and giggled, blushing lightly.

...

On Day 4, Rarity continued to spank and rub Sunset's butt, though it didn't feel quite the same with the mudslide in her pants, they both still liked it. The day went on the same as before, and Rarity gave Sunset more prunes. She was in a sitting position the next time she messed herself, and she thoroughly enjoyed it this time.

...

On the night of Day 5, Sunset peed again. She had soiled herself again today, and Rarity had peed on her again. She of course had peed and farted more times than she could count, and she smelled really bad. But, both she and Rarity loved it.

"Well, that's the end of the dare," said Rarity. "The other girls get back tomorrow." She untied the very wet and very smelly Sunset.

"Aw, does it have to end now?" said Sunset.

"We can keep it going if you want the other girls to find out."

Sunset blushed. "No, you're right. But let's set this up again some other time. Hey, you said you had Applejack do that to you, right?"

"Yes, of course."

"Maybe we can tell her, and she can do that to both of us."

"We could do that. I mean, she and I kind of have a thing going, but she said she likes to satisfy Rainbow Dash's fetishes as well, and I'm sure she'd love to."

"Well, I think it's time we take a long bubble bath and a shower," said Rarity. "You smell absolutely foul, and I've been wearing the same pair of underwear I peed in for three days straight. And, after you soiled yourself the first time, I ate some of the prunes too and didn't use toilet paper after."

"Well, you're still cleaner than me right now," said Sunset. She and Rarity giggled, and then started the bubble bath.

...

The next day, Sunset took her pajamas out of the dryer, which were spotlessly clean and smelled only of laundry that had just come out of the dryer. Her panties were stained slightly at the butt, but she didn't mind. Sunset herself no longer smelled of pee, poop, farts, and sweat, having cleaned up as nicely as her pajama pants.

That afternoon, Sunset and Rarity reunited with the other girls at the airport.

"Did you have a good trip?" said Sunset.

"It was really fun!" said Rainbow Dash. "Applejack and I won by a landslide!"

"And the museum was really..." began Twilight. "Uh, I hope it wasn't too boring back here."

"Rarity and I had lots of fun together," said Sunset, and she and Rarity did the rump bump.