Cooper Mullen is the husband of Debbie Mullen and a secondary narrator in Dear Debbie. He is an accountant in his “late forties” (21) and is described as being “good looking in that cute, boy-next-door sort of way” (21). For most of the book, the reader is led to believe that Cooper is having an affair with Harley. It is eventually revealed that Cooper is not hiding an affair, but is instead hiding his alcohol dependency, reflecting The Danger of Secrecy in Relationships.

In the novel’s final chapters, it is revealed that Cooper has been hiding his alcohol dependency for over 20 years, since before he and Debbie were married. Cooper justifies this decades-long lie by explaining that, “before we were married, I was scared that […] she would lose respect for me” (285), and after they were married, he was afraid “she would be furious with me for lying to her” (285). He attributes this fear to Debbie’s “impossible standard” (55) for him as her husband. Rather than address Debbie directly, he assumes the worst: “Christ what will she think of me?” (95). However, the novel suggests that Cooper’s fears about his wife’s opinions are far overblown. When Cooper finally admits his alcohol dependency and reveals that he has been attending meetings, Debbie is compassionate and understanding.

Despite Cooper’s fears, Debbie believes that Cooper has “many good qualities: he’s a good husband, a good father, and a damn good accountant” (23). Throughout the novel, Debbie maintains her faith that “he is very, very loyal” (286) and that he finds her “just as attractive as the day we met” (22), despite the red herrings pointing towards an affair. However, the novel also provides some hints that Cooper is not a perfect husband. Cooper admits that he doesn’t read Debbie’s column regularly and finds it “difficult” (294) to remember his daughters’ birthdays or his wife’s license plate number. This lack of attention leads Cooper to ignore crucial warning signs about his wife’s mental health. When the normally fastidious Debbie forgets to make his lunch, Cooper is “hurt” (26). Later, when she fails to make dinner for the family, he again takes it personally rather than questioning if something is wrong with Debbie. These details suggest that, despite Debbie’s love for Cooper, he is not a perfect husband.

Harley Sibbern is a friend of Debbie Mullen and the primary antagonist of Dear Debbie. She is a secondary narrator in the novel, although her perspective is unreliable because she is being lied to by Jesse Hutchinson, whom she knows as Cooper Mullen. She is in her mid-thirties and is described as having an alternative style, with “multiple piercings in each ear” (51) and a “pink streak laced through her blond hair” (51). Debbie’s chapters stress that Harley is unlike anyone else in her life: Debbie describes her as “cool” (50, 51), “hip” (51), and “self-assured” (51).

Harley is characterized by her tendency to use people and her desperation for the security of a real relationship. This tendency is best seen in her relationship with Debbie, who spends most of the novel believing that her friendship with Harley is genuine. Debbie believes that “Harley is the first friend I’ve had who is just for me” (50), and relishes the fact that she and Harley are able “to talk about other things besides…well, kids” (50). However, Harley later admits, “there’s only one reason why I’ve become friends with Debbie Mullen, and that’s to pump her for information about Cooper” (163). These passages suggest that Harley took advantage of Debbie’s need for a real friend to improve her illicit relationship with the man she believes to be Debbie’s husband. Harley’s later admission that it was “almost exhilarating” (162) when Debbie found Jesse’s shirt suggests that she actually takes pleasure in hurting her friend. Harley’s self-centered nature distinguishes her from Debbie, whose violence is rooted in a desire to protect others.

Despite Harley’s pattern of dating married men, the novel suggests that she is desperate for the security of a stable, monogamous relationship to the point of delusion. Even as she admits that her “relationships with men rarely end well” (103), she accepts every lie that “Cooper”—really Jesse Hutchinson in disguise—tells her. Harley’s desire for stability is so powerful that she often contradicts herself on the level of the sentence: “I know they’ll tell me what they think I want to hear, but I truly believe he doesn’t love Debbie anymore” (102). Here, Harley insists that “Cooper” is telling the truth even as she admits that men always lie to her. Harley’s desperation to force Cooper to leave his wife ultimately leads to her confrontation with Debbie, and to her death.

Jesse Hutchinson is an important antagonist in the novel and is known to each of the three narrators in different ways. He is a friend and colleague of Cooper Mullen and is also in a secret relationship with Harley Sibbern in which he uses the name “Cooper.” In college, he used the nickname “Hutch” when he met and raped Debbie Mullen. Debbie remembers him as a “cute” (197) man with “dark brown hair that curled endearingly at the ends and fell in his eyes” (197). As an adult, he is described by Harley as “really sexy” (99) and “in incredible shape” (104).

Jesse is characterized by his casual attitude towards rape, which reflects the novel’s thematic interest in misogyny and control of women’s bodies. Debbie recalls that, during her sexual assault, Jesse/Hutch responded to her pleas for him to stop with “annoyance” (199). Afterward, he left without speaking and “like nothing had happened” (199). Hutch’s attitude signals that he does not care about the gravity of his behavior. This is confirmed in the novel’s Epilogue, as an incarcerated Jesse recalls how he would sneak “ground-up sedatives” (310) into girls’ drinks and then “take them to my room [where] they didn’t protest too much” (310). Jesse insists that these sexual assaults “weren’t even a big deal” (310). Despite Jesse’s callous attitude towards rape, he takes violent means to protect himself from accusations, and the Epilogue reveals that he killed a woman named Misty Cardon, who threatened to expose him. Jesse’s repeated abuse of women reflects the influence of misogyny in modern culture. He dies in prison at the hands of other inmates who have discovered the details of his violence against women.