Karen broke off there, though, when she leaned forward a bit to prove her point and felt a noticeable shift in her underwear. That made her yelp and make tears start coming to her eyes, also motivating her to shout out, “I no do poo-poo!”

“Karen, shhh….” The ten-year-old infant was just kept from bawling when her mother bent low over her highchair and hugged her. “Don’t cry, sweetie, it’s just a dirty diaper. You don’t have to be in it for long…”

“Buh-But…” Turning even redder every passing second, Karen weakly protested, “I-I don’t get dirty diapies. Notta baby..”

“Awww, poor baby…” Patting the child on the back, the adult replied, “Baby or not, you want that diaper off, don’tcha?”

There was a long moment of consideration there, until finally the big baby was motivated to nod reluctantly.

“Poor thing,” her grandma commented at once. Smiling, after a moment, though, she began to offer, “I can take care of that if you’d rather.”

“Um, actually…” Dillion clearly didn’t sound too happy to put this out, but he felt obligated to explain, “I kind of promised her earlier that if it happened I’d take care of it.”

“You sure?” Tony frowned a little at that, giving Dillion a quick look, “I was kinda hoping we could-”

To Karen’s immense surprise, as she sat in her dirty diaper, biting her lip and trying not to bawl, she blurted out in a shaky voice, “I wan’ Dilliooonnn!”

“Eheh… That settles that,” replied the former baby with an apologetic look. As he began unlocking his sister’s highchair, he told his cousin, “We’ll get to it in a second okay?”

“Heh, okay.” Frown turning into a little smile, Tony jokingly questioned, “May as well give the birthday girl what she wants, huh?”

“Yeah, couldn’t hurt.” Smiling himself as he helped Karen out of her seat and to her feet, Dillion asked his clearly upset sister, “You gonna be okay?”

“Nnn…” That was actually about all the girl could manage out. It was taking so much effort not to scream her head off that forming real words seemed just out of reach at the moment.

The edge, was thankfully taken off when Dillion gently took her thumb and guided it to her mouth, cuddling her as she took her to the next room, “Don’t cry, Karen. You’re gonna be clean in no time.”

“Naw cwyin’,” choked out the baby around her thumb.

“Heh. Of course not.”

As he set to leading his sister to another room, Dillion held her close to keep her calm. As he did, though, he did feel like teasing, “Heh. Aren’t you glad now I changed you from shorts to a dress?”

“Heeee, yeah….” Turning pink, the girl pulled her dress up and took a look at her diaper. “‘S’easier ‘den pullin’ my pants down.”

“Yeah.” There was a changing mat folded up in the corner that Dillion unrolled. “Just lie down and I’ll take care of it, okay?”

“Kay…” Feeling a bit more relaxed now, the girl promptly plopped down on the mat without thinking. Then, after feeling the “Squish” of her waste against her bottom, began bawling.

That didn’t do much to keep Dillion calm about this. Still, he flew into action, moving to tickle Karen’s tummy while he cooed out, “It’s okay! It’s okay! It’ll just be a minute…”

“B-But…” Focusing on her words in this state was impossible for the girl, so the most she could manage was a very stuttered, “P-puh-poopies…”

“I know, I know…” Petting the girl’s hair, Dillion softly replied, “Poopies. But you’re gonna get out of it real fast, okay? Your big brother’s here to change you.”

“Big brudduh…” babbled out the girl before lying on her back for her change. Sticking her thumb back in her mouth, she asked, “D-Do poopies awways feel wike ‘dis?”

“Well, um…” There was a sort of quiet for a moment, before Dillion explained, “I guess, yeah. Heh, I’ve seen you take it worse than this.”

 

That gave the girl something to think about. Rather hard to do, but as her diaper was untaped Karen did find herself just a little more able to focus. After a few moments, she was motivated to mumble out, “Y-You’s a good big brothuh…”

“Aww…” Feeling a little touched by that, Dillion gave the girl’s tummy a brief tickle before he began wiping her. “Well, you’re a really good little sister, y’know that?”

“Hehehee…” The girl was lost in giggling for a moment and thus couldn’t respond, but once she recovered, she was able to remark, “Uh… Wh-What makes me a good li’l’ sistuh?”

“Heh. Well, you’re cute. That’s a big perk.” Grinning as he worked in spite of the smell, Dillion questioned, “So how about it, what makes me a good big brother?”

That took a moment to answer, but only because Karen found herself rather enjoying the feeling of being cleaned up. Once she did register things enough to reply, however, she explained, “W-Well, you’re nice, an’ya think I’s cute, an’ when I do baby things ya dun’ geh mad…”

“Well…. yeah.” Dillion sounded someone confused by that idea. After he had finished powdering his sister, he unfolded a fresh diaper and began to slide it under her butt, “You’re a baby, it’s natural you’d do baby things. I can’t get mad at you for it.”

“Well… Yeah, but…” Karen began to squirm a little, “Don’tcha think-”

“Uh… Hold still, okay?”