Monica is the novel’s antagonist. However, Abby initially describes her assistant in glowing terms, stating, “Monica is absolutely a breath of fresh air. She’s in her early twenties, a recent college graduate with a degree in art and math, and sharp as a tack. She soaks in everything like a sponge” (14). The protagonist perceives parallels between Monica and her younger self, noting her assistant’s ambition and their superficial resemblance to each other. In the early days of their relationship, these similarities solidify Abby’s trust in Monica. However, later in the novel, they contribute to her growing certainty that the “younger, prettier version” of herself poses a significant threat (168).

Monica’s role as the Alders’ surrogate is central to the psychological tension of the novel. Her character is the catalyst for the narrative’s central conflict, introducing the theme of Deception and Trust in Relationships. Creatively gifted and a math “genius,” Monica channels her intellect into a devious plan to seduce Sam away from Abby. Initially, her offer to be a surrogate seems altruistic, but as the pregnancy progresses, her behavior raises red flags. Monica becomes increasingly involved in Abby and Sam’s lives, blurring boundaries and creating emotional turmoil.​ Her manipulations and hidden agenda to keep the baby highlight the often-overlooked emotional complexities of surrogacy agreements.

Monica’s chameleon-like physical appearance underlines her deceitful nature. Her initial declaration that she is “an open book” is reinforced by plain clothing and a cosmetic-free look that suggests an absence of artifice (49). Once pregnant, Monica’s red lipstick and low-cut outfits make her look like an entirely different woman, conveying her duplicitousness and predatory intentions toward Sam. The change signals her transformation from a helpful assistant into a threatening presence.

The turning point in Monica’s character arc is marked by revelations of dark secrets from her past. The testimonies of Monica’s stepmother and former roommate, suggesting that she is responsible for two murders, cast her mental instability in a more sinister light. The novel’s climax, in which Monica attempts to kill Abby and accidentally shoots Gertie, underscores her capacity for harm. Meanwhile, her unexpected survival of a suicide attempt means that she continues to cast a threatening shadow over the Adlers’ future happiness.

From the beginning of the novel, Abby establishes the happiness of her marriage to her husband, Sam, frequently referring to him as “perfect.” As a math professor, Sam is known as “Professor McHottie” among his female students due to his arresting good looks. Nevertheless, Abby has complete faith in him, confident that he would never cheat. Sam’s innate compassion and sincerity are reflected in his “really kind eyes” (20). Abby conveys her husband’s lack of interest in the image he projects when she observes, “He wears glasses because contacts are ‘pointless,’ he’s never bought a bottle of hair gel in his life, nor has he ever set foot in an Armani store” (19). His authenticity and transparency of character offer a stark contrast to Monica’s deceit and duplicitousness.

Sam is presented as a dependable partner. Equally committed to having a child, he is a comfort and support to Abby during the challenging years when they unsuccessfully try for a baby. Sam approaches the idea of surrogacy with initial skepticism, revealing a more cautious nature than his wife. His argument that they should adopt an older child instead underlines the Ethical Considerations in Surrogacy, as he suggests that helping a child in need is a more altruistic path to parenthood. However, despite Sam’s reservations, he shows empathy and understanding toward Abby’s frustration with the lengthy adoption process and longing for a newborn. Throughout the narrative, Sam is a stabilizing presence amid the unfolding tension. His emotional restraint contrasts with Abby’s growing anxiety, highlighting his role as a grounding force in their relationship.

A hapless innocent, Sam inadvertently drives the conflict between the protagonist and antagonist. As Monica becomes increasingly blatant in her attempts to lure Sam away from Abby, readers are encouraged to question whether he is as trustworthy as he appears. Despite fearing that Monica’s machinations may be working on her husband, Abby resists her friend’s advice to check Sam’s phone, wanting to preserve the trust between them. When Abby is framed for methamphetamine use, Sam doubts her claim of innocence due to her increasingly erratic behavior. However, his devotion to his wife is ultimately demonstrated when he risks his own life to save her.

Abby’s boss, Denise, is the chief marketing officer of Stewart Advertising. Denise’s formidable and intimidating presence is emphasized by her “ice-blue eyes and blond hair swept into a perfect French knot” (7). Single-minded and career driven, Denise perceives motherhood as a barrier to professional success, and her disapproval of Abby’s plans to take parental leave sparks conflict between them. Denise’s character illustrates the complexities of female relationships in the workplace, especially concerning ambition versus motherhood. Her view that women must choose between the two contrasts with Abby’s belief that women can have both a family and a rewarding career.

Early in the novel, Denise is depicted as an antagonist. Her insensitivity is illustrated when she messages Abby after learning that her adoption has failed to ask if she can cancel her parental leave. Furthermore, Denise’s criticisms of Abby’s performance at work seem overly harsh, exacerbating the protagonist’s anxiety. However, as the narrative progresses, it emerges that Denise’s critique of Abby is justified, as her professional competency has been impaired by methamphetamines. Meanwhile, Abby’s focus on Denise as an adversary distracts her from the much greater threat posed by Monica. Denise has no option but to fire Abby when she fails a drug test. However, she never loses sight of Abby’s former brilliance and unexpectedly becomes an ally who shares the protagonist’s mistrust of Monica.

When Monica murders Denise, Abby reassesses her relationship with her former boss. The protagonist recalls Denise as a positive female role model in a male-dominated environment when she started working at Stewart Advertising. Recognizing Abby’s potential, Denise taught her “how to dress, how to smile, and how to be confident” in order to gain professional respect (176). She was also a friend in whom Abby confided. The protagonist’s recollection of Denise’s attributes after her death demonstrates Monica’s success in warping the relationships of others.