What is intriguing is the technique of arabesque which Poe employs with his narrators. That is, there is often a pattern of returning to an initial disturbing idea.
In the "Tell-Tale Heart," for instance, the narrator's fixation is upon the eye of his victim,
...a pale blue eye with a film over it. Whenever it fell upon me my blood ran cold..
....I tried how steadily I could maintain the ray upon the eye..
Then, too, he becomes obsessed with the "hellish tattoo of the heart of the old man, a fixation that eventually causes the narrator to cry out and confess so that the sound will stop.
In another story, "The Cask of Amontillado," Poe's crazed narrator engages in arabesque with the niter that has formed upon the labrinyth of narrow chambers in the catacombs.
The Gothic element for Poe lies in the realm of the narrator, as well. For Poe, it is not so much preternatural beings that characters must fear; instead, the real horror lies within the human beings themselves and what they are capable of doing.
In "The Cask of Amontillado," for example, the relationship of Montresor and Fortunato has become perverted through Montresor's use of reverse psychology--"We will go back; you will be ill, and...there is Luchesi--"; "I drink...to your long life"--until finally, the the narrator cries out his victim's name.:
My heart grew sick--on account of the dampness of the catacombs. I hastened to make an end of my labor.
Here the narrator realizes the evil that lies within him and he feels a sense of horror for what he himself has done that overshadows his pride of accomplishment. Similarly, in "The Fall of the House of Usher," the mind of Roderick Usher is tortured by its own imaginings.