As part of her survival, “Rachel” develops for herself a set of rules to govern her conduct based on what has consistently kept her safe, and this serves as a motif for her resilience and tenacity. The first are called “Rules for Staying Alive in the Shed,” and the second, “Rules for Staying Alive Outside the Shed.” These sets of rules symbolize the degree to which “Rachel’s” cognition has shifted because of the trauma that she must continually endure. The rules allow her to exert a small measure of control and attempt to make sense of a terrifying and often unpredictable situation. While she has little control over her circumstances, “Rachel” can at least master her own mind; her thoughts are her own, and she has decided that she will not be defeated. Thus, she uses Aidan’s abnormal behavior against him, coding his reactions and reacting to his pathologies in ways that will allow her to survive her interactions with him.

When her limited world expands beyond the shed and she gains the opportunity to see him interacting with his daughter in his own environment, her set of rules likewise expands to accommodate this new dynamic. The rules for staying alive inside the shed are preestablished when “Rachel’s” character is first introduced, but because she modifies her survival rules considerably as the story unfolds, this inner strategy also serves a vital storytelling role, for each time she decides to add another rule to her list, the author delves more deeply into the protagonist’s thought processes as she determines the parameters that will direct her eventual escape.