Louise is simultaneously the protagonist and the villain of The Perfect Nanny. Hired by the Massés to care for Adam and Mila, two young children, Louise initially appears perfect: She works hard, going above and beyond her assigned duties; she is attentive to the children, who adore her; and, most importantly (to Paul and Myriam Massé, that is) she isn’t “other”. White, French, and lacking familial obligations, Louise checks every box for Paul and Myriam Massé—but this image of “the perfect nanny” is a stark contrast to the opening of the book, which states in no uncertain terms that Louise murdered the very children she was caring for.

As the story progresses, it becomes clear that Louise is, in fact, “other”. She doesn’t fit in with the other nannies, many of whom aren’t white and don’t speak French. Her lower socioeconomic rank sets her apart from the families she works for. Her maternal instincts, initially portrayed as a positive contrast to Myriam’s career-centric desires, erode over time, giving way to neglectful and violent tendencies. It is heavily implied that Louise bites Adam and blames it on Mila. Louise also has a history of mental health conditions, and was once a patient at Henri-Mondor hospital.