Kiana is an 8th-grade student temporarily attending Greenwich Middle School while her mother is filming a movie. Initially indifferent, she ends up in room 117 by mistake and becomes an accidental leader among her peers due to her willingness to engage with assignments.

Parker, a student in room 117, struggles with dyslexia, which affects his reading and writing. Despite these challenges, he shows intelligence and a kind nature, eventually receiving support that caters to his learning needs.

Aldo is a student with anger management issues placed in room 117 for being too disruptive. Throughout the story, he learns to manage his emotions better through the support of friends and a caring teacher.

Mateo is a smart, small student who interprets the world through pop culture references. He faces bullying for his unique perspective and appears to be in room 117 simply for being different.

Barnstorm is a former star athlete whose sports career was halted by an injury. He was coasting on athletic ability in school and faces challenges in redefining himself beyond his sports identity.

Emma Fountain is a young, engaged teacher and the daughter of Mr. Kermit's former girlfriend. She serves as a catalyst for change for Mr. Kermit by introducing innovative teaching methods and collaborating with his class.

Jake is a successful businessman who was responsible for the cheating scandal that affected Mr. Kermit's career 27 years ago. He is willing to make amends by helping Mr. Kermit and the students.

Elaine is an eighth grader with a reputation for violence based on her appearance and rumors. Her character illustrates how external perceptions can unfairly label students.

Dr. Thaddeus is the superintendent and former principal fixated on firing Mr. Kermit due to the scandal, despite knowing Mr. Kermit's innocence. He is concerned with maintaining a pristine school image.

Stepmomster is Kiana's stepmother, initially seen as a negative presence by Kiana, but later understood by Kiana to be a role model.

Grams is Parker's grandmother dealing with memory loss. Her care and shared moments with Parker motivate him throughout the story.

Mrs. Vargas is the principal of Greenwich Middle School. A supporter of Mr. Kermit's potential, she opposes Dr. Thaddeus's attempts to undermine him.

Rahim is often napping due to his father's band's rehearsals keeping him up at night. In room 117, Mr. Kermit helps him discover and nurture his artistic talent.