Lizzie Houser is the younger sister of the victim, Bryden Frost. She is 32 years old and single. She works as a nurse and lives near her sister’s apartment. Lizzie is a complex character who does not fit neatly into the role of either protagonist or antagonist. Her personality and her Emotional Response to Grief and Trauma evolve over the course of the novel, and she is even briefly considered as a suspect in her sister’s murder.

In the immediate aftermath of her sister’s disappearance, Lizzie takes on a leadership role by acting as a point of contact with the police, informing her parents, and arranging to pick them up from the airport. She uses her training as a nurse to “keep everyone else together, [and] to manage her own feelings as required” (21). Her parents, Sam, and the police find Lizzie’s “excitement” about the circumstances bizarre. The narrative reveals that although Lizzie “loved her sister […], their relationship had always been complicated” (188). Bryden was more popular, prettier, and more successful than Lizzie, which provoked Lizzie’s jealousy. With her sister gone, Lizzie feels that she can finally be recognized for her leadership abilities, and this is why she puts her true-crime obsession to what she perceives to be a beneficial use.

However, the longer the investigation continues, the more Lizzie isolates herself and disappears “down the rabbit hole” (253) of her online true-crime community, where she seeks to assert a measure of control over the investigation by posting suggestive comments about the case. Her behavior soon worries her mother, and Lizzie makes the questionable decision to release sensitive information about her sister’s murder to the online group. While her parents and the police are suspicious of these behaviors, Lizzie does this merely to seek some form of validation and attention in the midst of the family trauma.

Donna Houser is the mother of Bryden and Lizzie. She is a flat character who acts as a minor protagonist and serves largely to demonstrate the stereotypical reactions of a mother to losing a daughter to murder. When Lizzie first informs Donna of her sister’s disappearance, Donna becomes “hysterical,” and when Bryden’s body is found, she “gasps and begins to sob” before “let[ting] out an awful, blood-curdling shriek” (84). Later, as reality sets in, Donna becomes tortured with guilt, wondering if it was “a mistake” for her to move to Florida instead of “be[ing] here for her daughter” (107).

In the days following her daughter’s murder, Donna becomes increasingly paranoid and anxious. She lies awake at night, wondering who killed her daughter, and based on Sam’s “demeanor” and lack of alibi, she eventually decides that he is the culprit. As she tells Lizzie, “He’s not acting like an innocent man” (152). Donna’s suspicions are based on the common but incorrect expectation that truth or innocence can be evaluated by a person’s emotional responses and behaviors, but she fails to consider that everyone responds to trauma differently. Donna also directs her nervous energy toward her surviving daughter, becoming fixated on decoding Lizzie’s self-isolating behavior and even growing convinced that her daughter has a substance use problem, despite the lack of any concrete evidence to this effect. Donna’s emotional responses are collectively emblematic of the paranoia, guilt, and anxiety that a mother might feel after the murder of her child.

Paige Mason acts as the antagonist in She Didn’t See It Coming. Paige is Bryden’s best friend, but she takes advantage of this relationship and Bryden’s trust and murders Bryden in cold blood. Paige is “beautiful” and financially comfortable; she works as a “communications director at a firm in Albany” (68). However, her life reflects The Tension between Outward Appearances and Hidden Realities, for despite this seeming perfection, she is deeply unhappy. She is unable to find a partner who is willing to commit, and she wonders if “there [is] something wrong with her […] something that men sensed, that sent them running” (329).

This emptiness in Paige’s life leads her to envy Bryden’s life and seek to replace her. Paige begins to insinuate herself into the Frost household by “coming over in the evenings when Bryden was away, to keep [Sam] company and spend time with Clara” (149), and she kisses Sam after a couple glasses of wine. Their affair continues in secret for months, during which she builds a relationship with Clara and becomes her “favorite babysitter.”

Infatuated with Sam, Paige indulges in the fantasy that, with Bryden gone, Sam will fall in love with her, and she can take Bryden’s place as Sam’s wife and Clara’s mother. When it becomes clear that Sam does not love Paige as she loves him, she turns on him. She attempts to pin the murder on Sam, and only his alibi saves him. The novel ultimately shows that Paige is a selfish, cold person who is ruthlessly willing to do whatever it takes to get what she wants. In this way, she is similar to Alice Gardner, who also goes to great lengths to attain money, attention, and sex.

Sam Frost is a secondary character whose depiction shifts over the course of the narrative. Initially, he is portrayed as a hardworking husband and father. For example, he makes time for his three-year-old daughter Clara at breakfast, “entertaining her with silly faces, making her laugh” (7). He gives his wife a kiss goodbye as he leaves for work, and he has a good job as a “portfolio manager with Kleinberg Wealth” (7). However, this ideal image begins to fall apart. As details of his marriage to Bryden come to light, it becomes clear that Sam does not take on his share of “the childcare and household chores” (25), even though his wife’s career is just as demanding as his. He periodically loses his temper due to stress and physically abuses his wife because he “knew how to hurt her when he wanted to” (174). He then blames her for failing to stand up to him, and he embarks on a “reckless” affair with his wife’s best friend, Paige. When Paige becomes infatuated with him, he treats her carelessly and with indifference.

After his wife is murdered, Sam falls apart emotionally, showing no interest in caring for the emotional needs of his young daughter. He even obstructs the investigation out of his own self-interest, neglecting to reveal his substance abuse problems until he absolutely has to in order to save himself. Far from being the “Husband of the Year” (150), Sam is arrogant, selfish, and callous.