Rats are the most prevalent and important motif in “The Rats in the Walls.” Delapore and the cats are the only ones who can hear the rats. In reality, the rats are no longer there; Delapore is probably hearing supernatural echoes of the hordes of rats that used to live under Exham Priory. The rats fled when they no longer had continuous access to food.

Thornton explains to Delapore that his nightmares are telling him something, and the same is true of the rats. They are guiding Delapore to his inevitable discovery of the truth about his family and about himself. Rats connect to the theme of Family History and Identity. They are a supernatural or subconscious manifestation of the truth about the de la Poers. Even after the narrative’s climax, Delapore still says that he can hear rats in the hospital walls. This suggests that since he now knows the truth about who he is, he cannot return to the person he was before.

Along with Delapore, only the cats can hear the rats in the walls. Delapore’s cats, particularly Black Tom, are symbolic of truth and innate knowledge.