Stella Lane is one of the novel’s two protagonists and is the female love interest. Stella has dark hair, wears glasses, and is slender. For most of the novel, she wears exclusively work clothes, which includes button-up shirts and pencil skirts. Stella is also diagnosed with Asperger’s, a variation of autism. At the beginning of the novel, she is uncomfortable with her autism and sees it as something that negatively differentiates her from her peers. Some of the ways that her autism manifests include sensitivity to light, sounds, smells, and textures, as well as hyper fixation on topics she finds interesting and difficulty reading social cues. One of Stella’s fixations is her career of econometrics, which is the study of modeling economic systems using statistics and calculus. She is an only child and has a history of struggling with romantic relationships. This is particularly true for physical interactions and what spurs her to hire Michael in the first place – she believes that she needs to be taught how to have sex in a way that is enjoyable for her partner.

While in her arrangement with Michael, Stella branches out of her usual comfort zones. She tries new foods, purchases new clothes, goes out clubbing, and enters a wide range of physically intimate experiences that includes intercourse.