It's Only Milk - Part 2 (Patreon)

Belle frowned, bouncing on her bottom curiously, cheeks darkening as, indeed, she heard the tell-tale sound of a diaper crinkle... But, rather than coming from one of her charges, it was coming from her! She whimpered, looking down to see her dress - much shorter, and more childish, than what she'd remembered putting on that morning - and the thick bulk beneath it, covered by a pair of pink, plastic pants. As she pressed her hand to the padding, she felt a familiar sensation, one that was only amplified by feeling the other side as well, as her fingers pressed the sodden diaper against her sensitive skin.

How could this have happened?! The last thing she remembered, she'd been changing little Rhianna after her nap, then fixing her bottle for her... Since she'd been a bit later than usual, she'd used just a bit more of the medicine Rhianna's mommy had her add to her bottles, feeling sure that would make up for the lost time... And then...

Then what?! It was all a blur after that... She poked at her diaper again, trying to remember how she could have possibly wound up in it. It was so huge... It had to be one of Rhianna's overnight ones!

Before she could, she heard the nursery door open, her instincts taking over as she tried desperately to cover her huge diaper with her hands, before seeing Rhianna stride in, wearing a diaper, but one much thinner than Belle's. Belle toddled over to her, nearly stumbling and falling onto her padded bum several times in just a few, awkward steps.

"Whewe's my cwothes?" she demanded, the authority quickly draining from her voice when she heard herself, and the ridiculous lisp she'd somehow acquired. "I need them!"

"See, isn't she cute?" Rhianna asked, taking Belle aback at how well-formed her words were, how normal she sounded. A moment later, to Belle's horror, her mommy stepped into the room as well. Belle gasped, shuffling backwards, away from her, as if there was anywhere to run. 

"What do you have to say for yourself, young lady?" the woman asked. Belle was used to hearing that question directed towards Rhianna when she refused to take a nap, or threw a tantrum, or drew on the walls... It took a moment to process that she was the one being asked, and just how horrifying it was to be on the receiving end.

"I... I..." she stammered, until a soothing sensation came over her.

"Look at her!" Rhianna giggled. "She just told me she wanted to be the baby now, didn't you?" Belle tried to say no, only to find something blocking her mouth; instead, she shook her head. "Aww, she's being shy now... But she did, I swear! And look, I'm not a baby anymore... Check me again, I'm still dry! I only wet myself once since my nap, and I can talk like a big girl again!"

"I don't know..." Rhianna's mommy said skeptically.

"Just look!" Rhianna scurried out of the room, returning with a bottle. Immediately, Belle's tummy began to rumble, and she reached out for it instinctively when the girl handed it to her, realizing only then, as she removed it, that one of her thumbs had been in her mouth. 

Belle stopped herself, feeling suddenly silly. What was she doing?! "I don't need baba," she pouted.

"Yes, you do," Rhianna told her, soothingly. Belle blushed, a faint memory coming back to her, eyes darting to a spot across the nursery where she recalled dropping a sippy cup earlier that day, after taking a gulp or two of milk. Maybe Rhianna was right...

"See?!" Rhianna pointed at Belle as she lifted the bottle to her lips, still feeling a little ridiculous. "She knew what was in the bottle, and she drank it anyway, because she wants to be a baby!"

Belle's face screwed up in confusion for a split second; by then, the milk was already dribbling down her throat, and her mouth muscles were taking over, sucking happily on the bottle's nipple. Her other hand rose up to hold the bottle as well, and, as liquid poured into her from one end, she could feel it start trickling out of the other.

"I suppose you're right..." Rhianna's mommy conceded. "If she wants to be the baby that badly, I suppose I can't say no... You're still too little to look after her, though. I'll have to find a sitter for the two of you for a while... Then, eventually, if you can prove you're a big enough girl, I'll let you take over looking after Baby Belle here."

"No!" Belle whined. "I'm the babysitter, not her!" But, even if she hadn't burbled the words into her bottle of milk, by then, they wouldn't have been any more than goo's and ga's, as, a few moments later, she sank down to the floor to finish off her milk, babbling as happily as any other baby - at least, until she missed her next bottle time.