Princess Twilight Sparkle covered her head as the students walked through the halls of Canterlot High after the bell rang. She was in a strange world, she had been turned into a bizarre creature she had never seen before that couldn't use magic, and she now had to somehow win her crown back at the Fall Formal. She didn't know how this could get any worse.

Until, a feeling hit her that was the last thing she needed right now. She needed to pee. Badly. She had forgotten to go before she left Equestria.

She made her way through the crowd to the bathrooms. She looked at the two doors, which each had a symbol on them. She remembered which one she had walked into that was the boys' bathroom before, so she figured the other one must be the girls' bathroom. She walked into that bathroom, hoping that whatever was inside the stalls wouldn't be something complicated that she also didn't know about.

To her relief, she saw familiar-looking toilets inside the stalls. This should be easy. She would have sighed in relief, except that her bladder was still full.

Twilight ran into a stall and closed the door. She grabbed the lock with her mouth and closed it, set her backpack containing Spike on the floor, and then sat on the toilet, lifting her skirt around her.

As she started to pee, she let out a sigh of relief, but then she realized that something felt off. She could hear her pee splashing into the toilet, but she could also feel a warm and wet sensation around her crotch and butt, as if she was wetting herself.

She lifted her skirt up and gasped. She was wearing something underneath her skirt, something she didn't recognize because ponies didn't wear it under their dresses. It was red, and only seemed to cover her nether regions, being less than shorts. She noticed how all of these creatures seemed to be wearing something, and her outfit had just materialized out of thin air when she transformed. They must not be as comfortable showing their butts and crotch areas as ponies were. She considered asking Fluttershy what this garment was, but knew that it might arouse suspicion. Besides, if her theory was right, then Fluttershy might not be comfortable talking about it.

Twilight was still peeing, and she knew that whatever this part of her outfit was, was already soaking wet, so she didn't try to pull it down. She blushed a little, even though no one could see it. She, a princess of Equestria, was wetting herself. This was so undignified.

Once she finished, she stood up. Her skirt hid the wet part of her outfit well, and she walked out of the stall.

Spike, who had respectfully looked away while Twilight was on the toilet, poked his head out of her backpack and sniffed. "Twilight, did you get a little pee on your dress?"

Twilight blushed beet red. "No, I... I'm wearing something else under my dress that I didn't know about. I don't know what this is exactly, except that it's wet now. Please don't tell anyone."

Spike laughed, and then said "Of course I won't. Besides, I'm not supposed to talk in front of anyone here, remember?"

...

Twilight had to stay in her wet state for the entire day, but no one noticed, as her skirt remained dry - until Fluttershy accidentally splashed fruit juice all over the front of her skirt at the cafeteria.

While at the school library, Twilight noticed a clothing magazine, and took a look at it. Flipping through the pages, she recognized what she was wearing underneath her skirt as soon as she saw it. It was called "panties". She was a little perplexed as to why it seemed to be plural, but it also seemed to go by the name "underwear". At least she wouldn't have to ask Fluttershy now.

When she was trying to adjust to what she was, dropping a stack of library books and trying to work a photocopying machine, eventually she needed to pee again, more so than last time due to all she had drank in the past few hours.

She ran into the bathroom, and into one of the stalls, closing it the same way as last time. She tried to reach her panties with her mouth, but couldn't bend that far in this form. She knew she couldn't use magic either, so she tried to pull them down with her hands. However, because she wasn't used to her hands yet, she couldn't get a firm enough grip on them to pull them down. She might have been able to if she could focus clearly on it, but she needed to pee really badly and was in a rush to get them down.

"Come on, come on, come on!" said Twilight, desperately trying to get a hold on her panties. "I really have to go! I don't wanna wet myself again!"

After a few minutes of this, she couldn't hold it anymore, and started to pee uncontrollably. There was nothing for it but to sit on the toilet, lifting her skirt out of the line of fire. For the second time today, she peed through her underwear into the toilet, with a mixed sigh of relief and dismay. This time felt a little more embarrassing in that she had just lost control and peed herself involuntarily.

She was sure a bit of pee had gotten on her skirt before she sat down, but it had already dried from the fruit juice, and she was sure this would dry faster.

Fortunately, this was one place Snips and Snails didn't follow her, since they'd likely get in trouble for spying on someone in the bathroom. So whatever else they recorded, no one but Spike would ever know she wet herself.

...

She slept in the library that night, in a bed Spike made out of books. Her panties were damp when she went to sleep, but dried overnight.

The following morning, she woke up and stretched. Once again, she noticed an urge to pee, as she often did first thing in the morning. She was sure she would end up peeing herself a third time, but she at least had to make an effort not to, so she made her way to the library bathroom.

She entered a stall and tried to pull her panties down, noticing in the process that they were dry now. She hoped they'd stay that way, but she wasn't very anxious about wetting herself, since she'd already done it twice.

To her relief, she was able to grab her panties and pull them down this time. She sat on the toilet with her skirt positioned correctly, and sighed of immense relief as she peed. She had a feeling this was the last time she would wet herself.

She lifted her panties up and sniffed. They still smelled of urine, but it was less noticeable than when they were wet, and she figured one would have to be right next to her crotch or butt to notice, and she had a feeling that... whatever she was... didn't push each other's butts with their heads like ponies often did. At least, she hoped they didn't, but as they walked on two legs, it seemed unlikely they would.

She'd have to wear her soiled underwear for the rest of her time here, even if she changed into something else, but as they were dry now she didn't mind.

Once she finished peeing, she put her panties back on and flushed. She kind of felt like she'd just been potty trained again.

She exited the bathroom, completely dry, and began compiling a list of talking points to win over all the school groups so she could become Princess of the Fall Formal. She was still a little nervous, but feeling more confident.