Chris is a high school student whose previously stable, model-daughter life is upended when she discovers she has contracted a sexually transmitted infection known as the "Bug." Facing stigmatization and changing peer dynamics, she struggles to balance her family's expectations with her new reality. Her story focuses on her physical changes, emerging sexuality, and her search for acceptance.

Keith is a listless high school student who feels alienated from his immediate friend group and anxious about his transition into adulthood. He harbors a strong, somewhat obsessive crush on his lab partner, Chris, which distracts him from the destructive behavior of his peers. He struggles to conform to traditional masculine expectations while seeking genuine emotional intimacy.

Eliza is a young woman and artist who resides in the basement of Burt's house to escape her troubled home life. She has the Bug, which manifests as a physical tail, and endures frequent mockery from her housemates who call her the "Lizard Queen." Despite her harsh environment, she cultivates a space of vulnerability and creativity through her drawing and sculpting.

Rob is a high school student attempting to manage the social and physical repercussions of contracting the Bug. His mutation includes a second mouth near his throat, which involuntarily voices his subconscious thoughts. He struggles with feelings of guilt and attempts to maintain relationships amid the complications of his illness.

Dave is a teenager living in self-exile at a camp in the woods after contracting the Bug. Having experienced intense bullying prior to his illness, he harbors deep resentment toward his peers. He develops a fierce, obsessive crush on Chris, viewing her as the only person who treats him with basic decency.

Todd is one of Keith's primary friends, characterized by his frequent drug use and aggressive, dismissive attitude toward others. He eagerly participates in bullying peers who are deemed unpopular or who have contracted the Bug, completely lacking empathy for those at the margins of their high school hierarchy.

Dee is Keith's other close friend, frequently found alongside Todd using drugs and attending parties. He shares Todd's callousness, participating in the destruction of property belonging to outcasts and showing a distinct lack of concern for the comfort or consent of his romantic partners.

Burt is a local drug dealer whose house serves as a hangout spot for various disaffected youths. He visually resembles Todd and shares a similarly abrasive personality, frequently enabling an abusive environment in his home, particularly toward his tenant, Eliza.

Lisa is Rob's girlfriend early in the story. She has contracted the Bug, which causes webbing to grow between her fingers, and actively attempts to hide her mutation to pass as healthy. Her deep-seated insecurities about her illness make her intensely suspicious of Rob's fidelity.

Marci is Chris's best friend from high school. She represents the mainstream, normative teenage experience that Chris is abruptly pulled away from. Marci holds strong prejudices against those with the Bug, openly displaying disgust when she encounters them in public.

Rick is a former schoolmate who fled into the woods after contracting the Bug. Bullied relentlessly before his diagnosis, his self-exile is compounded by the cruelty of peers like Todd and Dee, leaving him isolated and resentful in the forest.

Jill is a high school student who provides a space for her peers to hang out and drink. She attempts to keep her house orderly while dealing with the chaotic dynamics of the boys she invites over, often finding her own comfort disregarded.

Jill's older sister is a minor presence in the local party scene. She relies on drugs to cope with her own anxieties and quickly leaves the house to pursue her own complicated social life, offloading domestic responsibilities onto Jill.

Chris's mother is a strict parent who holds high standards for her daughter. Suspicious of Chris's recent behavior and absences, she grounds her and schedules medical appointments, inadvertently accelerating Chris's decision to flee her old life.

Chris's little brother is a young child who remains at home, representing the innocence and family stability that Chris leaves behind when her life changes.