Most of the characterization of Rosie is direct, meaning that Squeaky, the narrator, describes her specifically. There is also some indirect characterization because Rosie is described through her actions and words.
An example of the direct characterization is Squeaky’s introduction of Rosie. She is upset because Rosie makes fun of her brother Raymond, who has special needs.
Rosie … is as fat as I am skinny and has a big mouth where Raymond is concerned and is too stupid to know that there is not a big deal of difference between herself and Raymond and that she can’t afford to throw stones.
Rosie has also been hanging out with the new girl Gretchen. Rosie, Mary Louise, and Gretchen seem to go around together a lot. Squeaky is not included. She feels left out, because Mary Louise used to be her friend before Gretchen came. She never liked Rosie, because of her attitude apparently.
Squeaky describes Rosie as “salty.” By this she means that Rosie is sassy or rude.
“I don’t think you’re going to win this time,” says Rosie, trying to signify with her hands on her hips all salty, completely forgetting that I have whupped her behind many times for less salt than that.
When Squeaky tells them not to say anything about Raymond, Rosie sasses her with “What are you, his mother?” and Squeaky responds that she will be the mother of anyone who messes with him. Squeaky calls Rosie stupid and fat because she doesn’t like the way she acts toward Raymond. She feels that Rosie is mean, and they fight.
Squeaky is not afraid to stand up for herself, and not afraid to fight for Raymond. She feels that since he is different, she has to protect him. Mary Louise asks an innocent question about him, but Rosie turns the conversation mean and that’s when Squeaky gets threatening. That is an example of indirect characterization of Rosie.