One word sums up the narrator in Edgar Allan Poe's story "The Black Cat": sociopath. A sociopath doesn't respect laws or social rules, disregards others' rights, displays emotional and violent behavior, and fails to feel remorse or guilt for wrong actions. The narrator in this story is a middle-aged man whose behavior deteriorates to the point of murder. We only have the narrator's words by which to judge him, and he tells us from the beginning he is not a trustworthy narrator, for he says in the first sentence, "I neither expect nor solicit belief." Not only does this reveal his untrustworthy nature, but it also indicates that this man spurns approval or acceptance by others--he is anti-social. In the second paragraph, he makes sure we know that the "docility and humanity of my disposition" was remarkable from the time he was a baby. This statement we take with a huge grain of salt. The likelier scenario is that, as a child, he was a terror, but he saw himself as peaceful and loving.
An example he gives of what a kind person he was is that he took in many pets as a child. However, reading between the lines here, we can guess that he didn't like people and they didn't like him, and that's what led him to embrace the company of animals. His estrangement from people could well have been caused by his lack of respect for social rules.
Nevertheless, the man does marry, and his wife takes in pets. Perhaps this is because she is not getting her companionship needs met by her husband. As the years go by, the man turns to alcohol, and to this he attributes the fact that he "grew, day by day, more moody, more irritable, more regardless of the feelings of others." This shows other characteristics of a sociopath: emotional, violent, and heedless of others' rights. Indeed, he verbally abuses and beats his wife. He cuts out Pluto's eye with his pen knife, and he eventually murders the cat.
Through all these episodes, the narrator cannot feel true remorse. The level of remorse he feels is "a feeble and equivocal feeling, and the soul remained untouched." Although in the first part of the story he blames his actions on his "disease" of alcoholism, in the second part he has dropped that excuse and the second black cat becomes the thing that causes him to act the way he does. He never fully takes responsibility for his actions. Even in the process of writing his confession, he can never quite confess, for in the penultimate sentence he attributes his actions to the "hideous beast whose craft had seduced me into murder."
In this story, Poe has given us the portrait of a sociopath.