Keith Pearson is the second of the novel’s two protagonists. Like Chris, Keith is a high school student. His narrative arc revolves around reckoning with the listlessness he feels as an adolescent, which reflects his social environment—in particular, a friend group from which he is emotionally alienated.

In the novel’s early chapters, Keith is defined by his desire to be with Chris, who is his crush. Keith believes that being with Chris will help him to feel secure in an uncertain future, which he glimpses in the first chapter and finds terrifying. He never shares these desires and anxieties with his friends and is thus often distracted in their company, speaking more frequently in internal monologue than he does in dialogue with them. Todd and Dee observe that Keith wants to be somewhere else rather than in the present moment, but they fail to recognize that this is because he feels uncomfortable in the situations they bring him into, like the ones at Burt’s and Jill’s houses. His distraction is therefore a defense mechanism to avoid confronting his friends’ bullying and abusive behaviors. 

Keith’s arc centers heavily on the theme of Developing Healthy Attitudes Toward Sex and Intimacy as he distances himself from his friends’ attitudes and behaviors. In Chapter 2, Keith finds a girl’s skin and recognizes the intimacy of seeing marks that hint at the girl’s past. This fills him with sadness as he becomes conscious of his isolation: “I felt sick…sick of myself…sick of being stuck out in the woods, stoned and alone” (19). He wants to be seen by someone the way he feels he sees the girl whose skin he has found. Ironically, however, this skin is later revealed to have belonged to Chris, underscoring Keith’s failure to understand the skin’s owner or, more broadly, Chris’s inner life. Keith manages to find this intimacy with Eliza, who encourages him to feel vulnerable around her, in sharp contrast to the conventional masculinity he felt obliged to perform around Chris. Keith’s evolving relationship to the Bug, associated as it is with social ostracism, illustrates this shift. Keith’s attraction to Eliza includes the acknowledgement that he is also attracted to her tail, the symptomatic mutation of her illness. Moreover, he does not wrestle with the prospect of getting the Bug when he has sex with her and afterward calmly accepts the routine of applying bandages to himself once he starts experiencing his own mutation. The solidarity he receives from the people who have the Bug at the camp helps facilitate this change in attitude, and he later extends mutual support by bringing them food supplies.

Keith’s coming-of-age story thus shows him grappling with his place in the world. After Keith retreats from his friend group in Chapter 10, he tries to fill the gap of their absence with work. Keith gets a haircut and works multiple jobs, including one at the supermarket and another where he is housesitting for family friends, the McCroskys. He starts dressing more formally in the latter half of the book, which suggests that he has turned away from the counterculture his friends in some ways embodied (e.g., via their drug use) and is embracing a life of conformity. When he reunites with Chris at the camp, he finds an opportunity to fulfill his initial desire to be with her. He becomes disillusioned with this desire as he learns the truth about the challenges she has faced with her illness, as well as her relationship with Rob. Moreover, his crush indirectly ruins his job, as Chris brings the other camp residents over to the McCrosky house. When Dave kills the other residents, Keith decides to abandon the route of conformity and define maturity and stability for himself by embracing the intimacy he has found with Eliza. His narrative ends with him promising to settle down with her somewhere new, no longer distracted by a desire to be anywhere but the present moment.

Eliza is Keith’s romantic interest. She first appears in Chapter 7 and is introduced as the sole female resident of Burt’s house. Eliza’s relationship to Burt isn’t initially clear, but she explains it in Chapter 18 when she reveals her backstory to him. There, Eliza implies that she is a survivor of her stepfather’s sexual abuse, precipitating her escape from home. During her initial attempts to run away, she camped out in the woods but was haunted by the violence she witnessed there, including one incident where she saw a boy gagged and bound to a tree. This would influence her work as an artist, as she depicts similarly dark and violent imagery in her sketches. She accepted Burt’s offer to move into the extra room in his basement, thinking that he and his friends were harmless because she perceived them as “nerdy.” However, the men became increasingly abusive toward her, culminating in an act of physical and sexual violence against her while she was unconscious. Eliza discarded her artwork in the aftermath of this incident and soon moved out, after which she began a process of recovery.

Eliza is a major supporting character, though the fact that she is depicted through Keith’s perspective renders her largely flat. Her sexual history and her relationship with Keith anchor most of her characterization. There are a few hints regarding her broader life, such as her art, her school life, and her relationship with her biological father, but these remain largely unexplored over the course of the novel. Consequently, she functions primarily as an alternative romantic interest to Chris—one whose attraction to Keith is never complicated by any tensions within her character as she invites him to be vulnerable with her.

Rob Facincani is Chris’s romantic interest. He is the person who gives Chris the Bug, though in sleeping with her, he was acting under the misconception that Chris was aware of his illness. 

Around the same time that he has sex with Chris, Rob is in a relationship with a girl named Lisa. Lisa suspects that Rob wants Chris instead of her because Chris does not yet have the Bug, accusing him of being disgusted with Lisa for having it. Rob denies that this is the case, though Lisa’s suspicion is fueled by Rob’s second mouth, which voices his subconscious thoughts while he is sleeping and expresses his attraction to Chris. Besides underscoring the Bug’s association with broken sexual mores (e.g., standards that judge teen girls more harshly than boys for their sexual activity), this episode furthers the plot. Because Rob is generally evasive when talking about his feelings, the second mouth often counteracts his intentions. It does this again at the end of Chapter 11, expressing doubts that things will last. This sparks fears within Chris, undermining the idyll of their day at the beach together. Broadly, Rob’s second mouth suggests his absence of control in the face of his evolving body and feelings, developing the theme of The Adolescent Fear of Change.

Rob’s second mouth gives his character some complexity by suggesting his unstated motivations and anxieties. Much like Eliza, however, Rob is otherwise a flat character who largely exists and functions in relation to Chris. His death at the hands of Rick Halstrom is motivated by Dave’s jealousy over Rob’s relationship with Chris. Its narrative impact is also limited to Chris, providing her with an additional challenge as she struggles to find a sense of normalcy living with the Bug.