I'm not sure specifically what the 'round belly girl story' is without more context. It could be a story about a girl with a round belly for various reasons like she's pregnant, has a medical condition, or it could be a more metaphorical or fictional description in a particular tale.
Since I don't know the details of the 'round belly girl story', it's hard to say who the main character is. But it's likely to be the girl with the round belly herself.
Once there was a kind old man with a big round belly. He loved to tell stories to the children in the village. His big belly would jiggle as he laughed while sharing his tales of far - off lands and magical creatures.
Maybe the story is about a group of friends who make fun of one of their friends with a big round belly at first. But then they get into trouble and the friend with the big round belly uses his belly in a unique way to save them all. For instance, his big round belly can act as a bouncy cushion when they fall from a height, teaching the others not to judge based on appearance.
I'm not entirely sure as it could be a very specific and perhaps fan - created concept. It might be a fanfic that focuses on Batman having a round belly, which could be a really unique take on the character, perhaps exploring a different version of him where he's let himself go a bit in terms of physical appearance and how that affects his crime - fighting or his relationships.
There could be stories from different cultures about boys with big round bellies. In some Asian cultures, there might be tales of boys with big bellies who were considered lucky or blessed. These boys were often depicted as having a jolly nature, and their big bellies were seen as a sign of good health and prosperity in the family.
One big round belly boy story could be about a little boy who ate too much at a fair. He had a big round belly after indulging in cotton candy, popcorn and hot dogs. His family laughed as he waddled around with his full tummy.
Once there was a girl named Lily. She loved to eat a lot of junk food. One day, she ate so much at a fair - cotton candy, fried dough, and huge ice creams. Soon after, her belly felt really heavy. She couldn't run around with her friends as she usually did. But then she realized she needed to change her diet and started eating healthier. After a while, her belly no longer felt heavy and she was back to her active self.
As I'm not acquainted with 'the round girl story', I can't accurately name the main characters. However, thinking about it, in addition to the girl who is the focus due to being 'round' in some way, there might be a mentor - like figure in the story, someone who helps the girl understand herself better. There could also be a antagonist, perhaps someone who teases or makes the girl feel bad about her 'roundness' at the start of the story, but through the course of the story, she overcomes this with the help of other positive characters.
Sorry, I don't have specific 'batman belly round fanfic' to recommend as it's a rather unusual and specific type of fanfic. You could try searching on popular fanfic websites and use those keywords to see if anything pops up.