by: Lady Lucia | Story In Progress | Last updated Jul 24, 2026
PART 51
Kate
What a day. What a fucking amazing day!
I didn’t actually think my older sister would put on pull-ups. When I first grabbed them off the shelf, it was mostly just to make a jab about her size. It was always so easy to get a rise out of her. Annelise is literally the most boring, stuck-up girl on the face of the planet. Her entire personality revolves around studying, and she always thinks that she knows best. And yet, I was the one blessed by puberty while she was stuck with a wonderfully short stature and barely existent curves.
As a girl who is forever trying to make up for the things that she lacks, of course she decided to literally put on pull-ups in the name of clinging to her full name. The funniest part, aside from the obvious fact that wearing babyish underwear is way more immature than simply putting up with a nickname, is that ‘Annie’ would be a pretty solid name if she just leaned into it. Instead, her obvious distaste and annoyance towards the nickname ended up being the very reason my friends and I gravitated towards it. Important life lesson, sis–never tell people the things that annoy you. That’s a surefire way to make said things into a constant tease.
That really should have been it. Little Annie wearing pull-ups was more than enough to make the day all kinds of amusing. Honestly, it wasn’t that complex of a plan–when we arrived, I was going to find a chance to pull her skirt down before she got a chance to change, and then stay true to my word about calling her ‘Annelise’ while she dealt with a much more embarrassing situation. Dare or no dare, being caught in pull-ups would be enough to make my ‘I’m so mature’ sister blush up a storm.
But then she kept letting me do things! I always knew Annelise wasn’t the best when it came to confrontation, but how could a sister of mine be such a pushover? First it was the sports drink down her pull-ups, after which she actually climbed into the car instead of storming off to change like I expected her to. Then I managed to give her an amazingly childish make-over, and got the chance to confiscate her phone and her bra. Little by little, dear Annie was turning more into my tween sister than anything else. And the worse she looked, the more her posturing seemed to come across as the whiny attitude of the brat she honestly was most of the time. In a different way, of course, but does it really make a difference? Either way, she’s not nearly as mature as she thinks she is.
Because, instead of speaking up and ignoring the impossible conditions I set upon her, Annelise WET her PULL-UPS.
Oh. My. Fucking. God.
It took everything in me not to lose my shit. An apt phrase, because I had to try. I knew she would do just about anything to keep her little accident a secret, so why not try and see just how far she’d go in the name of keeping a little outward dignity. To our parents, of course. And she actually did it! Annelise shit herself to keep me quiet about a secret that was suddenly infinitely worse than it was before.
I was beyond eager to trap her in the dirty underwear for as long as possible. Not only would it be a persistent reminder of just how far she had fallen in less than an afternoon, but I low key wanted to see my older sister with a diaper rash. She wore them while meeting our cousins, throughout the fashion show that was plenty amusing in itself, and then through a whole game of mini golf. All the while, doing whatever it took to keep me content. Pretending she was twelve, being way more bubbly than energetic than she was when she was actually that age, and perfectly fitting the role that I had impulsively cast her in when we arrived.
Technically, I wasn’t even blackmailing her. The whole time, I made a point to say just enough to let her get carried away with the implications herself instead of outright laying things out for her. True, there was a threat here and there to keep her in line, but those were when she was already behaving like the tween she deserved to be treated like. Little Annie. Maybe some time in diapers and a crash course in attitude adjustment would be just what she needed to come down from her tediously aloof and ‘I know better’ way of thinking. If you knew better, dear sister, you wouldn’t have let yourself get talked into putting on pull-ups.
Of course, there were some pieces of the puzzle Annelise didn’t know.
For starters, I told Aunt Miranda about Annie’s ‘accidents’ pretty early on, when Lilah and I were looking around for the twins’ old clothes. While I may be the golden child at home due to how I know how to work our parents, I’ve heard plenty of our mother’s phone calls to different relatives. She loves to talk up Annelise’s perfect grades, and potential career paths after college, etc. etc. And, since she has a habit of talking on speaker phone, I’ve had plenty of opportunities to listen in. Not that I really make an effort to do so. But it’s easy enough to ‘eavesdrop’ when the conversation is happening in the other room and not particularly hushed.
Point is, the majority of said relatives always have a hint of something in their tone when Annelise is brought up. Not annoyance or anything like that, but more that they’re probably tired of hearing the same thing over and over. Since I branch out with extracurriculars and other activities, there’s always been more ups and downs to share about me. Basically, I’m more interesting. My sister, on the other hand, is ‘perfect.’ At least, academically.
Long story short, I took a shot. Little Annie isn’t the only girl in our family that can do some basic math, and I figured that our aunt would statistically be tired of hearing about my sister’s successes. So I framed things just right to her. How the stress of college classes has been a lot for Annelise, and how she’s become a chronic bedwetter because of it. And, with the occasional daytime accident, she’s currently wearing diapers 24/7 until she can be trusted to wear normal underwear again without making a mess in public and embarrassing herself. How I came up with the idea that Annie should be ‘twelve’ this weekend, in case our cousins found out about her padded underwear. Finally, the little detail that she’s been acting out because of this whole situation.
Basically, enough for a woman like Aunt Miranda to seize the opportunity to take my uptight sister down a peg or two. Not maliciously, of course, but how could she resist when all she’s heard for years is how amazing Annelise is? I was careful to pull off the ‘thoughtful sister’ act the whole time, but also made sure to sound that I was capable of being firm as well once I brought up the behavior thing. All in all, I did a wonderful job painting myself as the more mature sister, all while setting up Annelise for failure. And Aunt Miranda went for it, as I got to witness when she pretended to go along with the ‘experiment’ story I made up. Being kind and subtly patronizing towards my older sister, and letting me go about my business without realizing that this was actually Annie’s first day putting on pull-ups and using them not long afterwards.
Next, I told the twins a real truth before they got in the car with me and Annie. Simplifying everything down, I basically showed them my sister’s driver’s license and told them that I had something on her that ensured she had to complete my ‘dare’ of pretending to be my little sister for the visit. Luna and Lilah were more than enthused to realize that they could be part of a game that involved making their older cousin put on this act as if she had to convince them even though they already knew.
Now it was Annie vs. the world. A clever eighteen year old sister, an aunt who was content to sit back and see little miss perfect seem more like a young adult who clearly couldn’t handle the stress of college classes, and two cousins who brought their own unique spin to my ever evolving game. It was going to be quite the weekend.
Changing Annelise was immensely satisfying as well. Seeing her like that? Legs spread, but not in a remotely sexual context. Soaked, messy pull-ups. An ‘accident’ of mostly her own making, and not at all the usual prim and proper girl she always tried so hard to be. I took my sweet time with the process and made sure to cake on enough baby powder for her to hopefully catch the scent every few minutes. And, of course, to hide the smell of yet another one she would be having after being all pinned up. Also, diapers were so much better than pull-ups; easier to change, too.
Finally, I grabbed a little capsule of suppositories when Annelise was ever so patiently waiting for me in the pharmacy bathroom. It was possible to coax that first ‘accident’ out of her in the car, but my brat of a sister would need a few more nudges to ensure she stayed diapered for more than a day or two. Since my gloved hand was pretty much everywhere thanks to how long she had been walking around in her dirty pull-ups, it was easy enough to slip my finger between her cheeks. Just for good measure, I inserted a second one. Since I wasn’t particularly well versed in medication like that, I had no idea how long it would take. Sooner was ideal, as it would be more difficult for Annie to use the toilet in time without my assistance.
I made sure to be such a good sister. It would be so embarrassing if little Annie’s diapers weren’t pinned up nice and tightly, as I couldn’t bear for my darling sister’s padded underwear to come loose underneath those cute shortalls. So I used the pliers on my multi-tool, and gave a nice pinch and twist to the metal on each of the pins. Maybe that would make it impossible for her to take them off herself, but that was a small price to pay for making sure the diapers stayed on all night. Or at least until I allowed her to take them off. After all, it’s not like a girl like her can be trusted with such decisions.
Sure enough, she seemed to have a bit of an emergency during dinner for some reason. Since she went off all on her lonesome, I simply stayed at the table and brought up the idea of camp in her absence. Pulling that off would be more complicated, but it would absolutely be worth it.
Diapered Annie, shipped off to camp instead of returning to her summer break.
The Road Trip
by: Lady Lucia | Story In Progress | Last updated Jul 24, 2026
Stories of Age/Time Transformation