I know I've said this a lot with these stories, but this is definitely the most 18+ thing I've posted here, so if you like your diaper stories on the sweet and wholesome side, this is probably not the story for you!

Matti was no stranger to feeling anxious at a time like this, even if she normally had no real reason to be. Her grades had always been great, and yet, she was always nervous when she showed them off. Her parents had never pressured her to make her feel like she had to be perfect, but she'd done that to herself, and if she wasn't, there was some tiny part of her that was certain everyone would be disappointed in her.

This was much different. For one thing, it wasn't her parents she was showing her grades to, it was Valerie, the cheerleader who was making her life a living nightmare, who had already taped her into a diaper, and was making Matti kneel on the floor in front of her bed as she looked over the webpage, wearing only that and the hoodie she'd worn over, keeping her jeans hostage, while Matti was filled with a constant sense of dread over the possibility of Valerie's roommate walking in on her.

For another, she knew that Valerie wanted something very different from her parents when she looked at her grades. And, unfortunately, she'd gotten her way, to some degree. More than once, after cheerleading practice, as Matti bit her tongue, knowing that protesting would mean she wouldn't get her panties back, and would have to go back to her dorm wearing the Pull-Ups Valerie made her wear to most practices, the girl had made Matti destroy one of her meticulously prepared assignments, throwing out all of her work and turning in something that she was frankly embarrassed to have her professors see coming from her.

But, as much as those had damaged her grades, it hadn't happened in every class, and she was still staying afloat, thanks to her tests, and other in-person things that Valerie couldn't affect, and how high her grades had been to begin with. In a way, it had made her even more proud of the couple classes where she was holding onto her usual A's.

"What is this?" Valerie shook her head. "I can't believe you!"

Unfortunately, Matti knew it was those same A's that Valerie was talking about, even before she turned the laptop around, jabbing her finger at them. "I-I haven't had enough time to get those grades down," Matti lied.

Valerie stared her in the eye, making Matti squirm in her diapers, a shiver running down her spine. To be totally honest, though, it wasn't a completely bad one, and she could feel a warmth building between her legs at the reminder of how much power Valerie held over her, thanks to the pictures and videos the girl had that Matti couldn't let her older sister see. This was an awful situation, one that was having real consequences in her life, as her grades were showing. She shouldn't be getting turned on by this at all, and yet, here she was, doing exactly that.

"Have you been trying?" Valerie demanded, and Matti couldn't find the strength to fib again. She shook her head. "I didn't think so. You still don't get it. These grades are all far, far too high for a little diaper bimbo like you."

"B-But that's a C!" Matti pointed it out. "Th-That's not good at all!" That letter that hadn't been on her report card in a very long time, if ever. As soon as she'd seen it the first time, she'd both felt like she wanted to throw up, and had barely stopped herself from reaching between her legs and starting to rub, looking at that tangible proof of what Valerie was doing to her.

"It's a start," Valerie admitted, "but not good enough. Fortunately, I had a feeling this was going to happen, so I called in a little favor from Dr. Osswald. She was concerned, too, and happy to let me borrow her classroom to help you out."

Dr. Osswald, no doubt, had been concerned for the completely opposite reason. She was a math professor, and Matti had always done well in her class, up until now. She had always been very nice to Matti, so Matti wasn't surprised that she'd been willing to help, although she'd probably have sang a different tune if she'd known what was actually going to happen.

"Wh-Why there?" Matti asked nervously. What did Valerie have planned?! It would be nice not to have to worry about the girl's roommate walking in on them, but this made her worry about how long whatever this was would take, considering how long she'd been kneeling there on the floor, with Valerie not appearing to care about any possible interruptions.

"Oh, you'll see," Valerie giggled, tossing Matti her jeans. "Put those on."

She'd had a feeling she'd end up in a diaper, so Matti had chosen some baggy jeans, and an oversized hoodie, which kept her diaper pretty well hidden. There was a decent chance she would have worn them anyway, of course, but they had come in handy in this case as she was led through the campus, cheeks pink anytime they got within a few feet of anyone else, terrified they'd hear her crinkling, or spot the slight toddle the diapers gave her, since they were just thick enough to prevent her from being able to completely close her legs.

Matti had spent plenty of time in Dr. Osswald's classroom, but it was surreal to watch Valerie take out a key and unlock it, and walk in to find it completely empty. "Wow," Matti breathed, looking around. "It seems so much bigger without anyone else in it."

"There's certainly plenty of room to give you an audience," Valerie sneered, though, thankfully, she locked the door and pulled the shade on the small window closed before she started to unbutton Matti's pants again.

"I-I can do it," Matti told her quietly, not really fighting it when Valerie continued anyway, sliding the jeans down Matti's legs, letting her step out of them. Matti knew there were some people online who talked about attending college classes in diapers, but she was nowhere near ready to attempt that. She'd already been anxious just being in this room with a diaper on, and now that it was mostly exposed, only the top somewhat hidden by her oversized hoodie, she could feel her heart fluttering, positive that the professor was going to walk in at any moment and discover her.

Dr. Osswald was very pretty, she had to admit, and tall, especially compared to the diminutive Matti. Matti was fairly certain she remembered hearing the woman say she had a daughter, too, so there was little doubt that she'd recognize the sight of a diaper, and know how to deal with someone she caught wearing one. Matti's face burned as she imagined that, wriggling in place as she waited to hear what Valerie wanted from her next.

"I thought this was the perfect place," Valerie explained, "not only because Dr. Osswald seems to like you for some reason, but also because I remembered from the math class I had to take from her that she had all those chalkboards."

She gestured up to the front of the room, where, indeed, there were four of them. Matti remembered being impressed by how many there were the first time she'd had a class here, but by now, she'd seen the professor use all of them at once, several times. They were all blank now, and Matti could see a footstool in front of one of them, along with something she couldn't quite make out on the wall beneath each of the four. "What are...?" she wrinkled her forehead, taking a step closer.

"Hold on," Valerie grabbed her by the hand, pulling her close and reaching into her purse, taking out a tube of bright red lipstick. "Pucker up!"

"Huh?" Matti frowned.

"Come on," Valerie rolled her eyes. "I know you don't bother with it usually, but you can't tell me you don't know how to put it on at all."

Matti blinked. "Th-That's for me?"

Valerie sighed. "Of course it is, dummy! Now pucker up!"

Matti obeyed, wrinkling her nose as she felt the makeup being smeared across her lips. It was true, she had worn it a couple times, always at Kelsey's prompting, and with Kelsey doing it for her. She'd hated it every time, and even this seemed strange to her, as simple as it was.

"Much better," Valerie declared. "Now you're ready." She tossed her purse onto a nearby desk and led Matti down the steps to the front of the room. Matti was almost too distracted by the way the crinkling of her diaper echoed throughout the empty room, her imagination running wild, conjuring up an image of her being the first person to class, and Dr. Osswald hearing that from beneath her clothes as she slunk to her seat, feeling the woman's eyes on her, knowing from the look in her eyes that she knew what that sound was, thanks to hearing it from her own daughter however long ago she'd been in diapers, to pay attention to what was underneath the chalkboards.

The closer she got, however, the harder that was to ignore. When, finally, she realized what it was, she stopped in her tracks, her whole body warming a few degrees. "Wh-What are those?" she asked, staring at them, not even daring to point, not wanting to look at them.

"Oh, please," Valerie sniffed. "I know you aren't THAT innocent, Mathilda."

And she wasn't. Matti could see that they were dildos, stuck to the wall under the right side of each chalkboard, jutting straight out obscenely. That didn't tell her why, though. "B-But what...?" she blushed, unable to finish the question.

"Your performance with the bottles," Valerie told her, Matti turning and even darker shade of red as she remembered that, "was so pathetic, I realized you needed far more training. This is a very important skill for a little diaper slut like you to have, so I want to help you perfect it."

Matti gasped, her mouth falling open in shock. "Yes," Valerie smirked, stroking Matti's jaw before the girl could say anything. "That's a good start. I know you're just a beginner, sweetie, so I don't expect you to take the whole thing right away. But I want to see you get your mouth all the way around it, at least, and I want to see you making an effort to go further each time. That's why there's one for each board! So we can see your progress!"

"I don't wanna make any progress!" Matti stomped her foot, the wet stickiness she could feel in her diaper betraying her protests, reminding her that, no matter, or perhaps because of, how mortifying this was, there was still a part of her that was finding all this hot. It wasn't real, after all. Those things weren't attached to anything, they were silicone and nothing more, no matter what they looked like.

"I was hoping we wouldn't have to use all of them," Valerie ignored her, not sounding like she meant her words at all. "That is your fault. You see, each of these boards represents a letter grade. If you got a D, you'd only have to use one of them, and then two for a C, and so on. If you'd gotten an F, like a good girl, you could have a reward instead. But you didn't, did you? You had to get an A. And that means all four."

Matti had worked hard all of her life to avoid getting any F's, and now, the only way to avoid this humiliation was to let herself get one. She had to bite her lip, not trusting herself to speak out, worried she'd betray herself, let out a little moan as her mind absorbed how absurd this was, how twisted.

"As much fun as it has been, 'helping' you with your homework," Valerie continued, "I can't do that all the time. So this is to help encourage you to do it on your own."

"S-So I just...?" Matti took a tentative step forward, face nearly as bright red as her lipstick.

"Someone's eager!" Valerie giggled, watching Matti blush even more. "Not yet, silly. You need to do the rest of your punishment first! I want you to fill this board for me. You're going to write, 'I am an obedient little diaper bimbo' as many times as it takes to fill the entire board, and then you can give it your first try."

Matti's stomach lurched as she glanced at all four boards, her wrist already starting to ache. Valerie really was trying to discourage her from getting any A's in the future. "B-But..." she stammered.

"I suggest you get moving," Valerie said, strutting back to fetch her purse, and then returning to a front row seat, taking out her phone to no doubt record the whole thing, giving her even more ammunition to use against Matti, to keep her trapped under her thumb.

Matti groaned, picking up a piece of chalk and stepping onto the waiting footstool, and even then having to get up onto her tiptoes to reach the top of the board, making her hoodie ride up and exposing even more of her diaper to the lens of Valerie's camera. Hands shaking, she started to write, the words making her stomach flutter even before she was done with them, and the finished sentence almost making her light-headed when she saw it.

'I am an obedient little diaper bimbo.' A part of her knew that wasn't true, but another wasn't so sure. She was doing this, after all. She might not have much of a choice, but she could always take a chance on Kelsey taking her side, and not judging her for her newly discovered fetish. She was nowhere near ready for that, however, which meant that all she could do was obediently continue on, even knowing what awaited for her at the bottom of the board.

The words never quite lost their sting the more she wrote them, especially not when she finished the first row and stepped back, rubbing her hand on her hoodie. Looking back up, seeing all of those lines staring down at her, made them seem so much more real, crashing down on her like a wave, knowing there was room for at least one more row of them, if not more, meaning she had to do it all over again.

It was almost a relief when she was finished, despite what she knew she was going to have to do to cap it off. After writing the words so many times, having them drilled into her head over and over, there was a tiny part of her that wondered if there was any truth to it.

Gulping, she knelt down, blushing as she looked up at the dildo. She hoped Valerie would say she was joking, and that she'd had enough punishment, but that never came, leaving her no choice except to open her mouth wide and lean forward. She whimpered as it filled her mouth, gagging almost instantly and starting to pull away on instinct.

"Don't you dare!" Valerie warned her. "If you don't leave a nice, perfect ring so we can see how far you got, I'm going to make you erase that board and start all over again!"

Matti knew she couldn't do that, and so, reluctantly, she closed her mouth around the shaft, which felt even more wrong than just having it in there, praying that she was doing it right, and she hadn't messed up somehow as she knelt there, looking up at the board, desperate not to have to re-do it.

"All right," Valerie said, stepping up behind her. "Let's see." Matti wrinkled her nose as she pulled her head back, shocked at how close to the tip the circle of lipstick was, for how full her mouth had felt. "Well, there's plenty of room for improvement," Valerie told her, taking out the lipstick again to re-apply it. "But we all have to start somewhere."

"Y-You don't really want me to do this again, do you?" Matti sniffled, glancing at the next chalkboard over with dismay.

"I do," Valerie told her, patting her on the padded bottom. "This is what you get for those grades, young lady." For good grades, Matti reminded herself with a blush. This was what she got for getting good grades. "Now, for this board, I want you to write, 'I am a stupid little diaper bimbo.'" Valerie saw Matti's expression and grinned. "Because that's what you want to be, isn't it? Stupid little diaper bimbos who can't pass their classes don't have to deal with all this."

"N-No," Matti replied, her voice weak and quiet, and embarrassingly unconvincing. "I-I don't want..."

"Well, you will by the end of this," Valerie said. "Get started."

She wasn't even wrong, Matti had to admit. There was a part of her that wondered if it would be worth it to let her grades slip, if it meant avoiding at least part of this as she slowly worked her way down the board once, twice, three times, scrawling that mortifying phrase over and over, and knowing that, by the time she finished this, she was still only halfway done.

"Not much better," Valerie criticized, observing how far Matti managed to choke back the second dildo, "but it's something. Now, for the third board, your line is, 'I am a wet little diaper bimbo.'"

Matti blushed, wondering if Valerie knew the truth, if she could tell that, as tough as this was on her wrist, and as humiliated as she'd felt, wrapping her lips around those things on the wall, she was, indeed, still a little wet, still horny at what was being done to her.

"And you have an extra assignment this time," Valerie told her. "I want you to soak your diaper before you finish with your lines. If you haven't, you'll have to start this board over again, until you do."

Matti had no idea how long she'd been here, but her bladder had been feeling quite full by now, and she'd wondered if Valerie had wanted her to use it, right here in front of her, while she recorded this all on her phone. This definitely answered that question. Her face went red, but Valerie had already made her pee her pants in the middle of cheerleading practice, so doing it here, in relative privacy, while her face was staring at the chalkboard, even though it meant staring at those words, was simple in comparison. She barely paused her writing as she let go, feeling her diaper swell as it absorbed the warm urine.

She'd almost grown used to the feeling of her diaper by then, but it was completely different now, squishing between her thighs with her every move. Having brought that part of the line into reality, it felt, in a way, like she was confirming the rest, too, especially when she finished with the board and knelt down, her mind filled with some of the naughtier diaper stories she'd read, where little girls thanked their Daddies for changing their diapers and taking care of them by getting on their knees and unbuckling his belt...

That was what Valerie was doing, she realized. That was what she was training her for, turning her into. She'd gotten that sense somewhat with what had happened in the locker room, with the bottle, but it was so much stronger now. She knew she ought to refuse, to stand up for herself now, before things went any further.

Instead, she opened wide, and got a pat on the head. "Much better!" Valerie praised. "I knew you'd figure it out eventually! Just remember, you have to do even better next time! And your line for the last board is, 'I am a messy little diaper bimbo.'" Matti, still on her knees, gasped. "I guess you know what that means, then," Valerie chuckled.

"Valerie, no!" Matti shook her head. "I-I can't!"

"Then you're going to keep doing your lines, over and over, until you can," Valerie shrugged. "We have until Monday morning, when Dr. Osswald's first class starts. And, honestly, it won't bother me if it takes longer, though I suspect you won't feel the same."

"Valerie!" Matti squealed, squirming on the floor, looking out at all those seats, imagining them full of students, seeing her there, seeing what she'd written, and what she'd done to her diaper. "I-I mean it! I can't! I-I don't have to go!"

"We'll see about that," Valerie told her. "Go on."

Matti had only messed her diaper once, and, strangely enough, that had involved a chalkboard, too. She shuddered at the memory, of how much she'd been dreading all those punishments Ms. Emily had lined up for her, but also looking forward to them, in a way. She hadn't been able to control it then, thanks to the oatmeal she'd been fed. Now, it would be all her choice.

"What is that?" Valerie called from her seat. "That's not what I told you to write!"

Matti frowned, looking at the line she'd just finished, blushing when she read it. 'Good little girls make messes in their pants, not with their toys.' It wasn't what Valerie had said. It was what Ms. Emily had wanted her to write.

"S-Sorry!" she grabbed the eraser quickly, rubbing it out.

"What kind of messes are you making with your toys, Matti?" Valerie teased. Matti whimpered, unable to answer, concentrating harder on writing the correct line, not letting her attention stray.

As she approached the end of the board, Matti considered just doing as she'd been told, pooping her pants and getting it over with, but she couldn't make herself do it. She doubled down on her little fib as she put the final period on the last line, standing back to let Valerie see.

"Your diaper looks pretty clean from here," Valerie commented.

"I don't have to go!" Matti insisted. "There's nothing I can do about that!"

"I can think of one thing," Valerie told her. "Erase the board and start over."

"Valerie!" Matti stomped her foot. "This isn't fair!"

"Erase the board, Matti," Valerie ordered. "Or I'm going to write your sister a nice e-mail, and attach a bunch of very interesting pictures, and videos, and..."

"You're being ridiculous!" Matti glared. "I went before I came to your room! It's going to be..."

"Erase. The board." The cheerleader's tone silenced Matti instantly, and she picked up the eraser again, wiping away what felt like hours of work, and then stepping back onto the footstool to do it all over again.

For the first row, she was convinced she was going to stand her ground, positive that Valerie wouldn't make her do this a third time. By the time she was halfway through the second, she was less certain, and by the top of the third, all she wanted was for this to finally be over, no matter what it took. She couldn't write those words again, she just couldn't.

"I wouldn't wait until the last line if I were you," Valerie called. "If you do that, I might have to assume you haven't gotten it all out yet, and have you do your lines again while your tummy empties completely."

Matti growled, hating that Valerie had read her mind, had apparently seen through her lies about not having to poop in the first place. She tried to go back to writing, to wait it out so it didn't look like an immediate reaction to Valerie's words, but she was already so close to the end now, and she was too scared to test this latest threat.

She closed her eyes, bent her knees, and pushed. It was so much different than what had happened at the daycare, where she'd eventually just lost all control because she'd been holding it so long. She had to pretend she was alone, in the bathroom, and even then, after a few moments of pushing, her body tried to put a stop to it when it felt resistance as the warm mush met the soft, squishy padding of her diaper. She whined, tears stinging her eyes as she started again, grunting and groaning as she slowly filled her diaper, right in front of Valerie and her stupid camera.

"That's a big lump back there for someone who just used the potty not that long ago!" Valerie mocked.

Matti couldn't talk, not least of all because she was still straining, too scared of giving Valerie any excuse to tell her it wasn't good enough, and she'd have to re-do her lines. If the cheerleader wanted a dirty diaper, that was what she was going to get. After all, as her first set of lines had told her, she was nothing if not obedient. And she definitely felt pretty stupid, being forced to do all this, and there was no hiding the fact that she was wet, and now messy. And if all of that was true, did it mean she really was a diaper bimbo, too?

That was definitely how she felt as she carefully got to her knees, mass shifting in her pants, reminding her of the shameful thing she'd done. "I really need you to try, Matti," Valerie told her, coming up behind her to get a closer look. "If you don't do better than last time, you're not getting a clean diaper before I send you back to your own room."

"I-I don't need a diaper," Matti said softly.

"Really? That's not what all of these lines say." Valerie gave the seat of Matti's diaper a swat, spreading the mush further, making the girl squeak. "Or this diaper. You're definitely not getting those panties you wore to my room back after this. Now, show me what a good girl you are. Unless you want to stay like that."

"I-I don't," Matti shook her head.

"Then prove it." Valerie glanced over. "Prove to me you deserve it."

Matti had never felt more utterly humiliated in her life than right now, wearing a messy diaper, forcing the waiting dildo into her mouth, feeling it go in deeper and deeper, too scared that she was going to come up short to half-ass it, even when she saw Valerie gleefully snapping pictures.

"That's a good start," Valerie praised her. "You still have a lot to learn, but you did well."

This was not the sort of thing Matti wanted to be lauded for, but, after all of that, she was going to take what she could get.

"And since you did such a good job," Valerie said, "I found you a treat for next time."

"N-Next time?" Matti gulped.

"Oh, yes," Valerie smiled. "Your slip-up made me think of it, and then I found something that reminded me of your little dinosaur, and I couldn't resist. It should be here in a few days."

She showed Matti her phone, which did comfort Matti a touch, knowing she probably hadn't recorded the whole ordeal, at least, even if she'd almost definitely caught the part where Matti had pooped her pants. The picture Valerie showed her did look a lot like her brontosaurus hair clip, except there were a few spots on it that were clearly buttons, and a wire coming from the top.

"Wh-What...?" Matti squirmed, face bright red. "Wh-What does that go to?" she pointed a trembling finger at the wire.

"I guess you'll find out when it gets here," Valerie told her. "Now, why don't you go ahead and get the boards wiped off, and then I can change you? I'll get the changing mat set up."

As much as Matti would like to get out of this dirty diaper, she was glad, if Valerie was going to insist on changing her herself, that she was going to have a little time to cool down first. And, as humiliating as being changed in one of her classrooms was, it was definitely better than having to walk back across campus in messy pants. "O-Okay," she agreed, not feeling up to arguing any of it for fear of Valerie changing her mind about all of it.

"Don't sound so enthusiastic," Valerie giggled. "I'm not going to be too strict about this. You don't have to do it at all if you don't want to. Of course, if you don't want whoever's in Dr. Osswald's first class to see..."

"I-I'll do it!" Matti squealed. That would be bad, obviously, but the students wouldn't know who had done it. Dr. Osswald herself, however? She'd surely have a pretty good idea.

"I had a feeling you would," Valerie said. By the time Matti was done, she had a whole changing station set up and waiting for her. "I'm so proud of you," she gushed as she cleaned Matti up. "You worked off one whole A already!"

"W-Wait," Matti wiggled, frowning. "Th-That was only for one of the A's?"

"Oh, yes," Valerie grinned. "Don't worry, sweetie, Dr. Osswald is happy to let us use her classroom as many times as it takes until your grades are back where they ought to be."

Matti had a feeling that Dr. Osswald and Valerie had two very different goals for her grades, but the more Valerie succeeded in getting her way, the more it would look like she needed extra help, and the more Dr. Osswald would want to be sure she got it. And, as much as Matti desperately wanted to get A's, the way she always did, the thought of avoiding having to go through all this again was starting to seem more and more appealing, and perhaps worth an F or two...