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Heading up the steps of the von Einzbern castle, there was a nostalgic feeling within the King of Knights as she carried a small present with her. Today was a day she hadn’t celebrated in what felt like a decade now, not even since she was in the 4th Holy Grail War. However, she wasn’t carrying a gift for her master’s wife this time, but rather for an enemy master, technically. Although that was if she could still call Illyasviel von Einzbern her enemy since the war had finished, an odd conclusion that allowed not only the servant to make it all the way to November but the vessel for the Holy Grail too.
Without the war being considered, Saber had no particular disdain for Illyasviel, if not a liking towards the petite girl. After all, a decade ago had placed her at Illya’s mother’s side while her previous master did his usual galavanting around. There were many a fond memory that Saber still enjoyed, even if she hadn’t been around Illya all too much. Quite ironic, too, for how bloodthirsty she seemed at the beginning of the war, but that was different now as Saber knocked at the castle’s door.
Then she knocked again. And once more, just to be sure. To think that Illya wouldn’t be in her own home on her birthday was somewhat of a surprise after hearing her strained relationship with her grandfather, on top of not being clued into any parties at the Emiya residence or elsewhere. Well, at worst, Saber could leave the present, but a touch of curiosity filled her as she tried the large door’s handle. Just to make sure, of course, and lo and behold, the thumb latch gave way as the king sheltered herself inside from the brisk winter hair.
Perhaps it was just managing to get away from the cold, but a warmth comforted Saber once she was inside, staring around the entry hall as a decade-old familiarity reflected upon the interior of the castle. It almost felt like just yesterday that she was escorting Irisviel to the garage or helping her dress when she was too tired from dealing with Illya. More so since such a cute girl ended up needing some more help than usual as she was what others might call a late bloomer. Or more quite the late bloomer with how long it took to potty train the young lady. Throughout all of the war, she hadn’t heard anything to do with Illya being fully potty trained, and even now, Saber could just imagine Illya waddling down the stairs of the front hall in nothing but a diaper.
Er, well, maybe ‘imagine’ was an understatement as the King of Knights looked on to see just that: Illyasviel von Einzbern herself waddling down the stairs of the front hall in nothing but a diaper. The question was if she had realized that she had a guest as Saber was a little off to the side, not quite in the shadows but slightly behind a pillar, thus still out of sight if Illya wasn’t looking for her specifically. Although as she let Illya shuffle past towards the door to lock it, it felt less like she was a guest and more like an intruder at this point, leading to Saber clearing her voice. “Good afternoon, Illyasviel. It might be wise to make sure that you lock the door if you’re home alone in such, uh… sparse attire.”
A nostalgic pose struck the young girl as Saber watched on, reminding Saber of when Illya had tried to sneak some brownies when she was young. Of course, Illya had been caught then just as she was caught now, and in a diaper too. What a coincidence, and yet at the very least, the younger Illya would have turned around and pouted when caught. However, with how mature she was now, Illya was just frozen in place beside a couple of slight shivers and her knees buckling a little bit, as well as the soft echo of, “S-Saber?...” coming from Illya. The silence afterward is what got to Saber, though, as she slowly approached her previous master’s daughter, her soft footsteps the only noise in the hall before something pierced the air.
Illya farted. That was… ‘Unexpected’ was somewhat of the right word for the situation since Saber certainly didn’t expect that Illya would fart, the sound of which was muffled by the thickness of the diaper around her waist. On the other hand, said diaper completed the leap of logic for why Illya would unexpectedly fart like that since she’d have to be in a diaper for a reason. For what reason was the question, but as Saber reached a hand towards Illya, the smaller girl began to bend forward. “Not n-now, come on…! Sorry, Saber, but I-I going to poo-” Her words were cut off, but Saber caught the drift of what she was trying to say as she could hear the interruption coming from Illya’s rear.
Just as there was somewhat of an unexpected surprise before, another one came in the form of mushiness as Saber could hear, see, and certainly smell how much Illya was soiling herself. There didn’t even seem to be a moment for crackling before the sounds of squishing and squelching were coming from the petite girl’s rear. Despite having seen Illya soil herself when younger, seeing the birthday girl partially crouch as she was blowing out the rear of her diaper was quite something a whole decade later.
Such an infantile act was expected of just that, an infant. A young girl could be excused as well, but while Illya’s body size was that of a young girl, the mature lady of the house and the head of the von Einzbern family was not expected to soil herself. But here Saber was as she watched the pale girl’s diaper bulge out more and more as the sound of hissing followed. Not only was Illyasviel von Einzbern soiling herself, but the rest of her continence couldn’t hold it either as the last sputtering of Illya’s ass ended only a few moments before the muffled hissing finally died down.
Even if she was quite familiar with Illya being in a dirty diaper, Saber found there to be a slight awkwardness as her hand hovered just a little bit away from Illya’s shoulder. That hesitation disappeared, though, as she heard a small whimper from Illya, and Saber almost had to do a double-take as she wasn’t sure if she was staring at the current Illya or the little girl from a decade ago. But that didn’t matter as Saber responded just how she would either way: By wrapping her arms around Illya and giving her a tight hug. In such a moment, that’s the best Saber could do, but she could only hope it was enough.
Perhaps it was as Illya’s tension began to ease and that hissing from before started up again for just a moment. Saber knew the poor girl was embarrassed from being caught in such a manner, but at least it was her of all people that had caught the von Einzbern heir like this. “Now, Illya, you were potty-trained last that I saw, but now I’ve found you in such a full nappy of all underwear. Would you care to explain why, or would you prefer I change you instead?” Just like a decade ago, Illya’s poopy butt was ready to be taken care of by the servant, even if Saber’s master wasn’t as directly related to Illya anymore.
At least, even with the slightly greater degree of separation between them now, it wasn’t like Saber had found herself on bad terms with her former master’s daughter. Sure, there were a couple of instances with Illya’s own servant, but Saber could easily look past that when Illya was so adorable in nothing but such a dirty diaper as the knight shifted slightly away from the smaller girl to pull out the back of her diaper. “And Heaven knows you need it when your nappy is so full of poo. You messed a lot when you were younger too, so it’s nice to see that hasn’t changed in the least, even if you need one.”
Saber knew she was pushing the teasing a bit, and that was only confirmed as her finger was pulling out some air when Illya pulled away from the diaper check. Not unexpected, of course, as the blushing girl finally spoke. “It’s not as bad as you think! I just… Wait, how did you even get in here in the first place? I thought Sella… Oh, she must have had Leys lock the door again.”
Mumbling to herself in a huff, it took the von Einzbern heir a moment to get over her frustration at her maids before her face grew red again and she wagged a finger at her guest. “And you! It’s not my fault I pooped myself. You surprised me, that’s all! And like I said, it’s not that bad, I just, er… H-hold on…” Squatting a little in place again, Illya used Saber’s arms to steady herself as another short round of squelching erupted from her already-soiled rear.
Amid the young girl’s heavy panting, Saber could only sigh out with a soft laugh as she couldn’t believe that Illya really was still this much of a baby. “All done now? Or do you still have some more to get out?” A pouting headshake was all that she was given before Saber moved her arm around the poopy girl’s shoulder and led her along to the living room. “I suppose it wouldn’t hurt to leave you in your nappy as a small punishment if a mess like that can be called small.” A cute irony judging from her check before, on top of seeing Illya make her messy diaper even worse.
With only a small grumble in response, the King of Knights couldn’t help but enjoy how adorable the birthday girl currently was in nothing but her diaper, although a light went on over Saber’s head. “Ah, before I forget, I had talked to your maids about a present before. Incidentally, this seems to be the perfect occasion for it. Close your eyes and hold out your arms.” Illya seemed to easily follow the knight’s instructions as Saber pulled her gift out of the bag before stretching it a little to get it around Illya’s arms.
“Hey, Saber, what are you putting on me? I would think that Sella wouldn’t have the best taste in clothes unless they’re super-duper fan- Eh?!” If only Saber had a few seconds more but the von Einzbern heir found herself cuddled by a royal purple onesie, the buttons dangling on either side of her loaded underwear as getting it over such a full diaper would be quite the hassle. “This really is dizzying. Why would Leys and Sella tell you to get me a onesie of all things? They’re meant for babies!”
But even if they were, Illya’s hands were already exploring the softness as Saber quickly noticed. “And so are nappies, so I suppose it fits you quite well then. Come on, if things are that bad, you can some lie on my lap.” Squatting down to barely manage to get the buttons working past such a loaded diaper, a proud huff came from the king as she managed all three snaps. With that done, all that was left was to lead Illya over to the nearby couch before helping the petite pottypants lie down on her lap. “There, doesn’t that feel so much better? Just take a few deep breaths and relax, just as you used to do with your mother.” Even if Saber knew she wasn’t the same, it didn’t hurt to draw a familiar comparison.
Luckily for her, that seemed to do the trick as a little hesitancy at first melted into feeling the soft breath of Illya as she rested on the king’s lap, although the diaperdumper did pipe up still. “You know, even if you bring up Mama, I can still be mature. It’s my birthday, after all, so you can treat me like a big girl.” However, Saber noted a small groan from Illya as it felt like even Illya didn’t quite believe that lie.
Then again, who was Saber to disagree? If Illya wanted to be mature, then the king of knights knew exactly how to do that. “Hmm, mature, you say? Well, I suppose I could do something for you that I did with your mother. Just make sure to keep this a secret, especially from your grandfather: Your mother enjoyed wearing diapers too.” Holding a finger to her lip, her lack of breasts actually allowed her to see a glimmer in Illya’s eyes as she was almost a little surprised that Illya hadn’t known sooner. Irisviel was pretty discreet, though, especially as Saber added, “That’s so much of a secret that even Kiritsugu didn’t know. Or at least he never let on, but your mother only liked to do it around me, and it seems like you’re more than qualified to take up her mantle.”
Even if she was telling the truth, as Saber did have some fond memories despite what went on a decade ago, it was almost surprising that Illya hadn’t known about this before. “Come on! Tell me, tell me! Pleeeeaaaase? I wanna see what you did with Mama and her diapers.” Illya wasn’t her master, but the knight had teased the birthday girl enough as she slipped her hand by the buttons of Illya’s onesie and softly began to rub. Almost immediately, a hitched breath pierced the air, but Saber gave a smile towards her before Illya did her best to relax her head again, her thighs squirming around Saber’s hand all the while.
“Just relax, and I’ll show you instead~” Just that minor reaction from Illya felt like a decisive go-ahead already as Saber sped up the rubbing to the tune of squishing and squelching from how packed Illya’s pampers currently were. Those were familiar sounds, though, since Saber was almost surprised herself that Illya hadn’t soiled herself even more than this, but then again, perhaps it was her petite body compared to her mother’s that was the discrepancy. However, there wasn’t much of a difference in their reactions as Saber almost felt proud to hear Illya’s heavier breathing. “Getting close there, sweetie? Or can you hold on a little longer?”
Although she expected Illya to try to respond, a small chuckle escaped the servant as she heard the von Einzbern heir only whimper in response. To think she was so interested in indulging in Iri’s interests that she was fighting so hard, especially when the snow-white thighs pressed against her wrist. They didn’t inhibit the movement, though, but it was still a good reminder of just how effective this was on Illya since Saber didn’t quite know if the stinky little girl had much experience with this or if she had any experience at all.
Maybe more towards the latter as Illya’s wiggling only got worse, and that heavy breathing started to hitch. What surprised the knight, though, was some shifting below her as Illya moved her lower arm against her mouth to muffle her groans while Saber’s eyes widened for a moment once she felt Illya’s other hand on hers against her crotch. “There there, if you’re feeling close, don’t try to hold it. Just let it all out, and I’ll make sure to take care of it~” More nostalgia was filling Saber as she saw Illya’s face scrunch up before she swore that she heard Irisviel moaning, and so loudly too.
Like mother, like daughter, and so the king of knight’s hand felt the von Einzbern heir’s hips buck against it as she cooed more to Illya. “That’s it, don’t hold back. Your mother never certainly did.” Those must have been the magic words as the grinding stopped dead and the pale legs froze up before slowly settling back down against the couch with some little fidgets. However, when Saber had told her to let it all out, those little fidgets helped let loose a loud fart from the back.
Illya didn’t even seem like she cared, and Saber couldn’t blame her as no doubt that post-orgasm bliss had overtaken her. That was obvious enough by her heavy breathing and only further proven when the birthday girl’s big butt let loose a third mess into her diaper. Saber even noted some intermittent hissing, too, as no doubt it would be tough to hold it after cumming so hard. At least she was wearing her nappy, although the slight concern of leaks rose in Saber.
“From the sounds of it, it seems that you enjoyed yourself. I know this was for your birthday in particular, although admittedly, I enjoyed doing the same with your mother, and I certainly wouldn’t mind doing this again for you.” Lost in nostalgia for a moment, Saber took a deep breath before letting out a deep sigh. She was reminiscing about Illya’s mother a lot despite it being Illya’s birthday, and from the smell of it, there was another personal present she could give her. “Now, with that taken care of, perhaps we should get you a nappy change before your maids get upset about the couch cushions. How does that sound, Illya? Illya?...”
Looking back down at the girl resting on her lap, it shouldn’t have surprised Saber to see her softly napping now. The hand that once covered her moans now had her sucking her thumb as this was definitely something that the king of knights wasn’t used to. If she hadn’t thought that the pottypants was cute enough already, then Illya just further proved that to Saber as she slowly brushed her hand along Illya’s hair.
So much for talking about being so mature before, and yet Saber enjoyed the cutie in her diaper and onesie. “I suppose we can stay like this a while longer, although maybe next year, I’ll get you a plastic covering for the couch before your maids crucify me. Happy birthday, Illyasviel~”