"Bro? Broooo? Oh, right!" Charlote giggled and removed the fake belly ring, freeing you from your prison and giving you another poke.
"Yeah, I did" you answer. Charlotte stops her teasing for a second, surprised that you no longer are complaining and wondering if it's just another trick
"Are you serious bro? Did that actually worked?" She giggled. It was a ton of fun but she was clearly just messing around, she gasped with delight though when you told her "Yeah, I think so" in what sounded like a sincere tone.
Because you were still a bit confused about it, unable to tell at what point exactly did it stop feeling like you were a little boat trashed by a furious sea and it started feeling like something else, something exciting and cool and comforting at the same time, to the point it made you want to do exactly what she said and stay there as her "belly passenger" as she put it. Despite being digested gum, or body fuel, or whatever non human thing you were at the moment, your mind was still intact, and you were aware that something made you change your perspective from wanting to get out of here to wanting to stay, but even if you couldn't understand what exactly happened you knew you couldn't deny this comfortable feeling. Charlotte gave you another couple of pats and now you wanted to lean against her like some pet if you could, instead of protesting her annoying behavior.
"Hey bro.. Since you love it so much, why don't you tell me how it feels being there as part of me?" Charlotte asked, still amused and still not believing that belly dance routine could have changed your mind in such a stark way.
"I don't know how to describe it sis, at first it felt like being in a prison but now it feels like being in a really nice room, you know that feeling when you arrive home after a long trip? something like that" you blurt trying to make sense of those feelings yourself. It still strikes you as awkward but each time you embrace more that feeling, specially as your sister rewards you with a little caress of your "lump" which makes you escape a small happy squeak involuntarily, making you ask yourself if whatever she did is really turning you into some kind of pet.
"Aww, that's so nice!" Charlotte gushed, convinced you weren't lying for now and instead wondering how long your new docile behavior would stick, if you would still be hypnotized like that even after whenever she decided to take you out. "Now that you're no longer all grumpy, we can enjoy our day together, isn't that great?" she giggled when you answered her with a docile "yes, sis"
What happens next?