Raina is an 11-year-old sixth grader living in a San Francisco suburb. After a fall knocks out her two front teeth, she faces years of painful dental procedures, braces, and headgear. She has a strong creative side, enjoying cartoons, video games, and drawing. Her dental trauma causes deep self-esteem issues, making her desperate to fit in with her peers and find an ideal boyfriend.

Raina's mother is a protective presence who manages the logistical and emotional toll of her daughter's extensive dental care. She takes Raina to every appointment and advocates for her when doctors make mistakes. Though sometimes overprotective, she provides essential support and buys consolation gifts to help Raina cope with the pain.

Amara is Raina's younger sister and the middle child of the family. She uses Raina's dental issues as ammunition for sibling rivalry, frequently mocking her appearance. Beneath her teasing, she shares typical sibling dynamics with Raina, and their bond is tested during frightening experiences like a neighborhood earthquake.

Karin is one of the ringleaders of Raina's middle school friend group. She regularly mocks Raina impulsively, targeting her appearance, dental headgear, and crushes. She wears large hoop earrings as a status symbol and orchestrates mean-spirited pranks under the guise of friendship.

Nicole is a calculating member of Raina's friend group who thrives on targeting the vulnerable members of their social circle. She leaves a snide note in Raina's sixth-grade yearbook calling her "Vampire-Girl." She takes a primary role in organizing humiliating pranks, masking her bullying as innocent joking.

Raina's father works frequently and is less involved in the daily management of Raina's dental appointments. He is good-natured and friendly, keeping a calm demeanor during emergencies. He occasionally lacks a nuanced touch when dealing with his children's emotional struggles.

Will is the youngest child in the Telgemeier family. He is a baby and toddler throughout the story, requiring a stroller and car seat, and mostly observes the family's chaotic moments from the background.

Melissa is Raina's closest friend within her original Girl Scout group. She is naturally confident and serves as a confidant when she and Raina are away from the other girls. However, she frequently aligns with the broader group's opinions and tells Raina she takes jokes too seriously.

Emily serves as a secondary confidant to Raina within their social circle. She frequently criticizes Raina's appearance, pointing out her childish ponytails or discolored teeth. Her comments contribute to the peer pressure that makes Raina self-conscious as she enters adolescence.

Kelli is a member of Raina's friend group who feels guilty over her role in the accident, as Raina tripped while trying to grab her hoodie. She becomes gloomy as she enters puberty and mostly fades into the background of Raina's social life.

Sammy is a sixth grader who shares a mutual attraction with Raina. Because he also wears braces, he understands the physical and social discomfort Raina experiences. He has green eyes and makes earnest attempts to spend time with her, though Raina feels self-conscious about his younger age.

Sean is an athletic, basketball-playing transfer student who captures Raina's absolute attention. He is quiet, enjoys drawing, and represents an idealized boyfriend in Raina's daydreams, even though he barely speaks to her in reality.

Theresa is a high school student who notices and praises Raina's artwork. She is short, confident, and introduces Raina to a new, supportive circle of friends who appreciate her interests in cartoons and art rather than judging her appearance.

Dr. Dragoni is Raina's primary orthodontist. He maintains a relentlessly positive attitude, discussing even painful and difficult dental setbacks with a smile. While comforting on the surface, he occasionally lacks tact, asking Raina questions while her mouth is full of dental tools.

Dr. Golden is a children's dentist who treats Raina for much longer than is typical for his pediatric practice. He is friendly, calls Raina his star patient, and is honest about his disappointment when certain dental procedures do not heal as planned.

Jane is Raina's old best friend from fifth grade. She is less concerned with maturity and boys than Raina's current middle school group. Their friendship faces a disconnect when Raina visits and focuses heavily on her own appearance and boy troubles.

Kaylah is a member of Raina's circle who often endorses the actions of Karin and Nicole. She treats humiliating incidents as harmless pranks and laughs along with the others rather than defending Raina.

Jenny is a girl in Raina's friend group who already wears braces at the start of the story. She rattles off a list of forbidden foods for braces wearers, providing Raina's first glimpse into her upcoming lifestyle changes.