Dinnie, the protagonist, heroine and main character of Sharon Creech's novel Bloomability and she has several good friends and an aunt and uncle with her in Switzerland, where the novel is set. One of the friends is ironically the antagonist. The others are supporting characters and the aunt and uncle are additional characters who, nonetheless, play important roles.
First, the antagonist is Lila, another American student at the Swiss boarding school (an interesting aside is that Princess Diana attended a Swiss boarding school), is a griper and complainer who can't see that people from other cultures--or other cultures for that matter--have any sense or value. she also can't see that other ways of traditions and habits and social mores have equal value to (sometimes greater value than) American ways. Lila is therefore the antagonist. Should she ever overcome Dinnie with her petty small-minded ways, Dinnie would be a defeated heroine. Furthermore, if her constant harping on things causes Dinnie to close herself off to understanding and compassion, Dinnie will then be a corrupted heroine.
Guthrie, the charming American boy who has stolen the affections of both Dinnie and Lila, is the main supporting character. He represents Dinnie's right-hand assistant as she tries to adjust to her strange new situation and to Lila's embittered protestations about--well--everything she can think of. He even tries to help Dinnie understand Lila so that she doesn't join in with the general consensus and write Lila off as a lost cause. Guthrie is also a model for broadminded appreciation for and acceptance of cultures, languages and ways of life that are not American. He sets a good example for Dinnie to learn from and demonstrates that a person can choose their point of view and their attitude.
Dinnie's other friends, Spanish Belen and Japanese Keisuke, are minor supporting characters. They set examples of sound friendship and loving acceptance across cultural differences and deeply embedded traditions and expectations. Belen and Keisuke are girlfriend and boyfriend while at school but they must keep it a secret from their parents who, unlike their internationally educated children, are determined to uphold their separate traditional racial ways and have their children marry within their own cultures. Ironically, both sets of parents have created problems for themselves by giving their children such excellent and broadly inclusive educations. After Belen and Keisuke come Aunt Sandy and Uncle Max who represent adults who live the new all inclusive cultural and racial-ethnic standards the students are encountering and, hopefully, learning to embrace for life.