Simon Kelleher Simon is the creator of a popular gossip app that exposes students' secrets. Intelligent, observant, and manipulative, he enjoys using information to gain power over others. He carefully watches his classmates and knows many of their hidden lives. Simon's actions set the novel's central mystery in motion, and his influence continues to shape events even after his death.

Nate Macauley Nate is often labeled the school's "bad boy" because of his troubled home life and history of breaking rules. He is quiet, sarcastic, and distrustful of others, but beneath his tough exterior he is loyal and caring. Despite facing difficult circumstances, Nate has a strong sense of justice and gradually allows himself to trust and connect with others.

Bronwyn Rojas Bronwyn is an intelligent, ambitious student with excellent grades and dreams of attending an Ivy League university. She is logical, responsible, and usually follows the rules. Although she Rojas appears reserved, Bronwyn proves to be brave and compassionate. She questions assumptions, stands up for what she believes is right, and becomes more willing to take risks for the people she cares about.

Addy Prentiss Addy is known at school as the beautiful, popular homecoming princess. At first, she seems to fit the stereotype of someone who cares mostly about appearances and her relationship with her boyfriend. However, as the story unfolds, Addy becomes more independent and confident. She learns to make her own decisions instead of relying on others' approval, showing courage and emotional growth.

Cooper Clay Cooper is a talented baseball pitcher with a reputation as the hardworking, dependable athlete. Calm and thoughtful, he often tries to avoid drama and focus on his goals. Throughout the novel, he struggles with keeping a major personal secret hidden from others. As events unfold, he learns to embrace honesty and accept himself despite the risks.