Three of the main characters in the novel follow fixed routines that amount to obsessions. This recurring motif speaks to the theme of Developing Empathy. Harriet’s habits make perfect sense to her and provide her with a sense of security, but she lacks the empathy to understand the quirks of her two closest friends. Every day for five years, Harriet eats a tomato and mayonnaise sandwich for lunch. When she returns from school, she expects a snack of milk and cake to be ready for her. The cook is exasperated by these unvarying menu choices but provides them anyway.

Harriet follows a regular circuit when she makes her spy rounds. She always visits the same houses, usually in the same order. Of course, her most important recurring habit is that she writes down all her observations in her journal. The journal is a sort of security blanket for her because Harriet finds that she can’t think straight without it when her teachers confiscate it during class hours.

While Harriet’s friends and family find her behavior odd, she is far from the only character who indulges in a comforting and rigid routine. Sport proudly shows Harriet his financial ledgers.