Malú is a 12-year-old girl with dark hair, light brown skin, and dark eyes. She loves punk rock, making zines, and skateboarding. As a second-generation Mexican American with a white father, she frequently feels disconnected from her cultural heritage, preferring to express herself through her loud music and alternative fashion—like heavy eyeliner and silver-sequined sneakers.

Magaly Morales is a professor of Chicano Literature who moves her daughter to Chicago for a new teaching position. Nicknamed "SuperMexican" by Malú, she is deeply devoted to Mexican and Mexican American heritage. As a primary caregiver, she balances encouraging her daughter's independence with enforcing household rules and traditional cultural expectations.

Joe is a seventh-grade classmate of Malú's at José Guadalupe Posada Middle School. He plays the guitar, sketches well, and helps out at his parents' coffee shop, Calaca Coffee. Like Malú, he frequently alters his appearance and experiences a disconnect from the traditional expectations of his heritage.

Selena is a popular seventh-grader and leader of the Candy Crew, a clique known for wearing matching candy necklaces. She embraces her Mexican heritage through traditional dance but aggressively polices how others express their culture. She acts as the primary source of social friction for Malú and her friends at school.

Malú's Dad owns and operates Spins & Needles, a record shop in Gainesville, Florida. He is white and shares his deep love of punk music, vinyl records, and zine-making with his daughter. He acts as a supportive parent who offers Malú comfort from afar and encourages her to always remain true to herself.

Oralia is an elderly Mexican American woman who lives across the hall from Malú and her mom. She enjoys knitting and listening to traditional music like Lola Beltrán. She frequently dispenses gentle, grounded advice to her younger neighbors and serves as a calm, steadying presence in the apartment building.

Mrs. Hidalgo owns and operates Calaca Coffee in Chicago. She has pink hair, distinct cultural tattoos, and a deep appreciation for Mexican and Mexican American punk bands. She provides a living example of how to successfully merge traditional heritage with a rebellious, do-it-yourself aesthetic.

Benny is a middle school student who participates in the school marching band. He has a musical background, having previously played in a youth mariachi group with Joe. He is a talented trumpet player who reluctantly agrees to bring his skills to Malú's newly forming punk band.

Ellie is an ambitious, red-haired seventh-grader who is heavily focused on extracurriculars and building her future college applications. Though she has no prior musical experience, she agrees to learn the drums for Malú's band in exchange for petition signatures.

Principal Rivera is the head administrator at José Guadalupe Posada Middle School. She enforces school policies strictly and aims to protect the traditional nature of the school's 30th-anniversary Fall Fiesta, viewing alternative student plans as inappropriate disruptions.

Mrs. Ramirez is Selena's mother and the owner of the Ramirez Dance Studio, which teaches Mexican folkloric dance. She is strict about her daughter's extracurricular activities, insisting on traditional cultural dances rather than allowing exploration into other styles.

Mr. Jackson serves on the staff at the middle school. He handles student infractions like excessive makeup or brightly dyed hair, and he also communicates decisions about which students are allowed to participate in school events.

Diana is a seventh-grade student and a member of the popular Candy Crew clique. Like the rest of the group, she wears a signature candy necklace and largely follows Selena's social leads.

Ms. Hernandez is a homeroom teacher at the middle school. She enforces the school's rules and acts quickly when she spots students violating the dress code.

Mr. Hidalgo is Joe's father and Mrs. Ana Hidalgo's husband. He works alongside his wife to run the neighborhood coffee shop, providing a welcoming environment for the local community and his son's friends.