I've been working on Bella more and have finally gotten a good chunk of fun facts, Lore, and characterization down, so I can start diving into her character.
✿ Bella is autistic; her current hyperfixations are manners, research, and history and mythology are her biggest ones at the moment.
✿ Bella is a very quiet kid and likes to keep to herself since most people don't get her. However, when she becomes very curious about someone or something, all social norms and pleasantries  tend to go out the window. And she will become a very chatty, bubbly, and passionate child. 
✿ Bella has a one-sided beef with Felix. Because Bella loves to research things she gets very annoyed when people get things wrong about a topic she is very knowledgeable in so when her father introduced her to the Felix series she like it at first, but because Felix has a tendency to embellish things there’s a few things here and there that he gets wrong about certain things and areas he has seen which frustrates Bella greatly in fact, it has bother her so much she has sent multiple letters to the department of research to correct Felix on his books. She has received no replies and does not like him because of it.
✿ Bella is scared of hummingbirds.
✿ Bella will become very emotionally attached to random items, for example, her hat, which she refuses to leave the house without, and a certain blanket that she won't sleep without.
✿ Bella is an observant child. Bella knew at a very young age what the meaning behind many people's looks toward her meant. And she knew many of them held malicious intent. It’s not easy to be the only half-demon kid on the island.
✿ Bendy and Bella can have whole nonverbal conversations with their clicks. Personal headcanon: when demons are little, they communicate through the clicks they make, and when they are little, they have a much wider variety of pitches and sounds they can make to communicate what the little one needs, and as they get older, their clicks become less versatile as their voice develops more. 
✿ Bella can see the map, but cannot read it. She sees it like someone without their glasses would see the world: able to make out the general shape, with colors kind of there, but it’s overall very blurry and unreadable.
✿ Bella has a very cute giggle, it's a combo of a cute kid giggle mixed with the clicks her and Bendy make, it kinda sounds like a baby bird.
✿ Bella doesn't really have a sweet tooth; she only likes a few particular kinds of sweets. However, the sweets she does like, she goes crazy for. These are chocolate-covered fruits, ice cream, parfaits, strawberry shortcake, scones, lemon poppyseed muffins, and blueberry muffins.
✿ Bella is a very skilled writer. She loves to write research papers and books. She always keeps a science log (diary) about her everyday life. However, Bella isn't the most skilled artist; she struggles with it, and it frustrates her greatly.
✿ Bella is in the same phase Bendy was in when he was a toddler, where she’s already a very quiet kid, but on top of that, she will silently wander away from Bendy and Boris, and they have no idea where she is. It scares them every time she doesn’t cause trouble, which is good, but they sometimes have a hard time fighting her because of that.
