Well, the blueberry girl herself is obviously a main character. She's usually the center of the story with her unique traits. There might also be a sidekick, like a little talking animal that accompanies her on her adventures.
Since I don't know the exact 'blueberry girl story', it could be the blueberry girl herself as the main character. Maybe there's also a wise old owl that gives her advice on her journey.
Since I don't know the exact 'blueberry girl expansion story', it's hard to say for sure. But most likely, the blueberry girl herself would be a main character. There might also be characters like her family members, if the story is about her family life and how blueberries are part of it. Or perhaps there are friends she has who are involved in her blueberry - related adventures.
Since we don't know the details of the 'big blueberry girl story', it's hard to say for sure, but presumably the main character is the girl.
The main character is the blueberry girl. Since it's called the 'blueberry girl inflation story', she is likely at the center of whatever events are taking place. She could be a normal girl with a special connection to blueberries, and the inflation aspect could be something that happens to her directly, like a physical change, or something that affects her world around her.
Given the name 'blueberry boy story', the central character is no doubt the boy. But there could be other supporting characters. If it's a story about the boy's family business of growing blueberries, then his parents would be important characters. They could be teaching him the trade, passing on family secrets about blueberry cultivation. There might also be a local merchant who buys the blueberries from the boy's family, adding an element of commerce to the story. And if the story has a touch of magic, there could be a fairy or a spirit that guards the blueberry patch and has an interaction with the boy.
Since I don't know the exact 'blueberry graphic novel', I can't say for sure. But it's likely that Blueberry herself is a main character. There may also be her friends, family members, or some antagonists who oppose her in some way.
Obviously, Yn and Doctor Blueberry are the main characters. Yn is likely the protagonist who is new to the Underswap world, and Doctor Blueberry is an important figure in that world.
One interesting blueberry girl fanfiction could be about her magical adventures in a hidden forest. She might discover new powers and make friends with mystical creatures there.
Since I don't know the exact 'blueberry girls story', it's hard to say. But likely, the main characters are the blueberry girls themselves. There could also be supporting characters like their parents, friends in the neighborhood, or an old wise person who gives them advice related to blueberries or their adventures.
I'm not sure specifically as there could be various 'blueberry girl stories'. It might be about a girl who has a special connection to blueberries, like she lives on a blueberry farm or perhaps she discovers a magical blueberry that changes her life in some way.