In “A Tell-tale Heart” the narrator addresses us directly. Notice that Poe does not give any of the characters in this spooky story a name. Even though the narrator is using the second person to talk to us, we don’t know anything about him. Many mentally ill people talk to someone who is not there. It’s almost as if the narrator is addressing an imaginary person, rather than the reader.
Using the second person also allows the narrator to appeal to us directly. He spends a lot of time trying to defend his actions. Near the beginning of the story, he directs the reader to notice how clever he was in opening the door to peak in on the old man.
You fancy me mad. Madmen know nothing. But you should have seen me.
He reminds the reader that he is not crazy, and that he is in fact clever. This is the author’s way of reinforcing the idea that he really IS mad!