Bob Miller is another of the novel’s primary characters and first-person narrators. The chapters written from his first-person point of view are titled with his first name and depict episodes from his storyline, offering insight into his psyche.

Bob is an insecure, fearful character who will do anything to protect himself and acts as a foil to Sarah’s character. He is an arguably weaker character than her because, unlike Sarah, he doesn’t like to admit his contradictions or his more morally dubious tendencies. At times, he notices parallels between them, specifically when he’s referencing his and Sarah’s involvement in Kelly Summers’s death; he knows they both wanted revenge and that their shared participation in the murder brought them together. However, in the narrative present, Bob perpetually casts Sarah as the more devious and untrustworthy individual. He tries to convince everyone in his and Sarah’s lives that Sarah is more nefarious than they believe. While Sarah is indeed capable of criminal acts, Bob’s actions and behaviors often align with hers.

Bob’s determination to destroy Sarah throughout the novel underscores his unreliability and his cowardice. He never attempts to make amends for his past actions or appeal to Sarah’s softer side; he remains convinced that the sum of her character is her past actions. In failing to live with any integrity, Bob brings about his own demise. He falls into Sarah’s trap and becomes increasingly distraught over the course of the novel. The more convinced he is that Sarah is trying to hurt him, the more outrageous his actions become. Like Sarah, Bob is a static character who never fundamentally changes from who he was at the beginning of the novel; he dies essentially the same man he has been throughout.

Alejandro Perez is a secondary character. He first surfaces on the page when Bob selects him as the Morgan Foundation’s next “reformer,” or a formerly incarcerated person working with the foundation to re-enter society sustainably. When Sarah first meets Alejandro, she acts differently around him than she does the other foundation clients. She insists on filing his intake paperwork and forming a personal connection with him. She appeals to his more emotional side and commiserates with his frustrations with the justice system. She then goes so far as to hire Alejandro to complete odd jobs around her house.

For the first half of the novel, Sarah’s behaviors toward Alejandro suggest that Sarah and Alejandro have a connection; Sarah often acknowledges overlaps between their experiences and histories. Alejandro’s character also seems sensitive to Sarah in ways that others of the characters aren’t. He makes an effort to spend time with her and comforts her when Bob is mistreating her.

In a plot twist later in the novel, the narrative reveals that Alejandro has been working for Bob, who brought him to the foundation and tasked him with getting close to Sarah and then killing her.

However, in another twist, when Alejandro holds a gun to Sarah’s side after they have sex for the first time, Sarah privately reveals that she never trusted Alejandro or believed that he was who he said he was. Alejandro confirms her suspicions and explains who he is and how he knows Bob: He messed up Kelly Summers’s murder years prior and accidentally killed her husband, Bob’s brother Greg, instead. In the end, Alejandro teams up with Sarah to trick and destroy Bob, becoming another pawn in her game. His character also creates narrative tension and unexpected links between the characters in both the past and the present.

Kelly Summers is a minor character. Because she died years before the narrative present, she never appears in scene in The Perfect Divorce. However, her case is reopened at the start of the novel, making her character a key player in Sarah and Bob’s storylines. Kelly Summers was married to Bob’s brother Greg years before; Bob hated Kelly and hired Alejandro to kill her. Alejandro messed up the murder and mistakenly killed Greg. Convinced that Kelly killed Greg, Bob worked with Sarah to murder Kelly. Sarah was also eager to see Kelly dead because she was sleeping with Sarah’s then-husband Adam Morgan. Bob wanted to hire someone to kill Kelly, but Sarah insisted on doing the job herself, and then she and Bob framed Adam for the murder.

In the narrative present, new evidence surfaces implicating former police sheriff Ryan Stevens in the case. Sarah and Bob are terrified that they’ll be discovered; Stevens was also sleeping with Kelly and helped them pin her murder on Adam to protect himself. Kelly is the center of all the novel’s primary mysteries. The majority of the characters are connected because of Kelly. Her character is a device used to create tension and conflict and complicate the characters’ relationships with each other.

Stacy Howard is another of the novel’s minor characters, who first appears in scene soon after Stacy’s roommate reports her missing. They soon learn that Bob is allegedly the last person Stacy saw before she disappeared. When they call Bob in for questioning, he is shocked to discover that the missing woman is the same person he had a one-night stand with weeks prior. He was drunk and didn’t remember Stacy. He then cut her out of his life when Stacy tried to extort him, demanding that he pay her a large sum of money lest she tell his wife about their sexual encounter.

Like Alejandro and Kelly, Stacy is not a three-dimensional character, but her clichéd qualities make her an ideal narrative device. As a character, she also lacks dimension and dynamism because she is just a pawn in the primary characters’ worlds. Bob doesn’t really know anything about Stacy and slept with her just to escape his marriage. Sarah has no interest in who Stacy is but knows that she can use her to hurt Bob. In particular, Sarah kidnaps Stacy in order to frame Bob. She locks her in the basement of her remote lake house, drugs her, and manipulates her into believing that Bob abducted her and Carissa Brooks and is planning to kill her. In turn, Stacy murders Bob when she breaks free, effectively fulfilling Sarah’s master plan.