“The Rats in the Walls” is generally regarded as Lovecraft's finest Gothic piece.  Of course, he wrote other stories that can be safely classified as Gothic.  One example would be “The Outsider”. “The Hound” also has Gothic elements.  No other Lovecraft story in the Gothic tradition can be fairly considered the equal of “The Rats in the Walls.”

The narrator of “The Rats in the Walls” acquires a dark and ancient Gothic ruin, his family seat from generations past.  By inhabiting it, he inherits a forgotten family transgression.

As in “The Fall of the House of Usher,” the narrator is slowly drawn into the madness of the place.  The element of a force, pulling down on the house, remains, though it is twisted so that the force pulls down on the house's rightful heir, that is, the narrator.  The descent into madness is present,as is the explicit joining of the madness to the location.  The element of unexplained sounds leading up to the climax is also present .  The ending differs, and is noticeably more characteristic of Lovecraft than Poe.

There are specific textual details that reveal Lovecraft's intended connection between the two stories, as well.  For example, the word “house” refers, in both stories, to the physical building as well as the family that resides (or resided) there.  The narrator's ancient family name in “The Rats in the Walls” is “de la Poer,” clearly intended to evoke Poe's name. “de la Poer” conceals the name “e. a. Poe.”

The ending of “The Rats in the Walls” has given rise to much speculation.  Joshi believes that the climax is “a scenario that could only have occurred to a writer who had accepted the truth of the Darwinian theory.”  (Lovecraft, Annotated, 10)  Initially, the climax does seem to be a deliberate inversion of a Darwinian process.  This idea seems to be contradicted by the story's denouement, which appears to indicate that something else altogether was responsible for the events of the climax.  By investigating Lovecraft's letters, however, we do learn that he had a Darwinian idea in mind when writing this story.  In a 1923 letter to Frank Belknap Long, Lovecraft wrote,

“About the anthropological background of “The Rats” - undoubtedly you are right, although all deductions concerning primitive man are too nebulous to permit of dogmatism of any sort.  No line betwixt “human” and “non-human” organisms is possible,³ for all animate Nature is one - with differences only in degree, never in kind...” (Lovecraft, Lord, 122)

Lovecraft goes on to make comments about the transformation of gorillas into humans, which we now know is not the way it happened.  The point is, Lovecraft probably did have Darwinian concepts in mind when writing this story.  That said, if one were looking for a Lovecraft story involving his peculiar (and potentially offensive) ideas regarding Darwinian processes, one would be better advised to look at another of his somewhat Gothic tales, “Facts Concerning the Late Arthur Jermyn and His Family.”