Yoyo is an adolescent immigrant from the Dominican Republic trying to assimilate into her new life in New York. Known as the "Big Mouth" and spokesperson for her sisters, she experiences tension between her family's traditional values and the American culture surrounding her. She discovers a passion for the English language, using it to privately express her developing identity.

Laura is a Dominican mother adjusting to life in America by trying to invent new gadgets in her free time. Coming from a prominent family in her home country, she seeks a way to build personal recognition and independence in her new environment. She eagerly embraces American culture and English, even though she often mixes up idioms.

Carlos is a doctor and the patriarch of the García family. Having fled the violent Trujillo dictatorship, he carries deep trauma and a lingering fear of authority that influences how he parents. He resists his family's Americanization, insisting they speak Spanish at home and dreaming of an eventual return to his native country.

Sister Mary Joseph is a teacher at the Catholic school Yoyo and her sisters attend. She recognizes Yoyo's academic abilities and assigns her the responsibility of representing the student body.