Throughout the narrative, Lisa Jewell explores different versions of social invisibility—whether actively cultivated as a form of self-protection, deeply felt as a symptom of loneliness and discontent, or weaponized to conceal violence and misogyny— and its effects on the characters in her novel. While Saffyre uses invisibility to hide from her trauma and self-soothe, Roan uses invisibility as a psychiatrist to create the illusion that he is above reproach. Owen’s profound feelings of invisibility and loneliness make him highly susceptible to the influence of incel culture. Jewell uses this exploration to reveal her characters’ inner turmoil and highlight societal pressure, vulnerability, and safety.

Saffyre calls herself the titular “invisible girl” because of her desire to watch people without their knowledge. While Saffyre does not stalk people with malicious intentions, her behavior reveals the unaddressed trauma that she keeps hidden. Saffyre exhibits several traits of a person experiencing PTSD: She cannot sleep in her own bed, she feels chronically restless, and she attempts to disassociate from her own life and body through self-harm. Saffyre stalks people she wants to be close to, such as Roan—a desire that stems directly from her trauma and allows her to feel a sense of control of her life.