One of the characteristics of the narrator in the story "The Black Cat" by Edgar Allan Poe is the fact that he is unreliable. However, this is not evident from the beginning.
The narrator initially appears to be "sane," and it is only as the story progresses that the reader begins to doubt his mental capacity. This is achieved due to the fact that the narrator speaks to the reader directly. The use of this practice allows the reader to follow the mental processes of the narrator, allowing the reader to slowly notice his insanity.