Poe reveals character mostly via direct characterization of the narrator. The narrator describes himself as possessing "tenderness of heart" and a "fond[ness] for animals." He claims that he was happiest when he was "feeding and caressing" his many and varied pets, which were gifts from his parents while growing up. Further, he says that this love of animals grew with him into adulthood and that it is from this that he "derived . . . one of [his] principal sources of pleasure." Then, when he married, he was pleased to see that his wife shared this partiality for animals, and she immediately went to work in adopting several different animals to join their household. All of this detail is direct characterization: information about the character that is revealed directly and explicitly with no need for us to infer.
This direct characterization continues, even as the narrator experiences a change in his personality. He says that he "experienced a radical alteration for the worse." He grew more irritable and indifferent toward others' feelings, and he was even cruel to his wife. He neglected his pets and even mistreated them. The narrator directly names his "fiendish malevolence" on the night when he cut out his cat's eye. He also names the "spirit of perverseness" that consumes his person. All of this is direct characterization.
Character is defined through two distinct types of characterizations: direct and indirect characterization. Direct characterization is evident through the author defining exactly how a character is. The author hides nothing--naming the character through direct (explicit) details. For example, a direct characterization (from Edgar Allan Poe's "The Black Cat") exists when the narrator openly states "From my infancy I was noted for the docility and humanity of my disposition" Here, the speaker openly provides a characterization of himself for the reader (he is mild and humane).
Indirect characterization, on the other hand, is where the author provides information regarding a characterization through defining actions, interactions, or dialogue from which a reader must draw conclusions. In this, a reader must infer who a character is based upon the situations defined by the narrator or author. For example, the author openly states that he is not "mad." As the reader progresses through the story, he or she may come to challenge this statement. A reader, under these circumstances, should question the narrator's mental stability. Is a character who goes to the extent this narrator goes to really sane? The answer to this question provides an example of indirect characterization.