In the "the black cat"the narrator begins the story by speaking directly to the reader. the narrator continues this practice periodically throughout the story. how does the author's use of this structure create mystery in the story ?

Knowing that the narrator is speaking directly to you as the reader and giving only his perception of what happened leads to questions of whether or not he is a reliable narrator and lends an air of mystery to the story. In the opening of the story he even says he does not expect to be believed and that his “senses reject their own evidence,” so the reader cannot be sure of what is true

the rhetorical devices that he used in "common sense" are syntax for his sentence structure and pathos for his emotion against the british unfairly treating the "americans" and logos of what documents that what happened to the pilgrims when they had the mayflower compact and how that the british were wanting to have one religion but the compact said for any religion to be accepted.

its probably fingerprint or personality