Characters in "The Tell-Tale Heart"

"The Tell-Tale Heart" is a first-person narration. It helps us to understand the main character better.
So the author is the main character of the story. He is nervous, paranoid and mentally ill. He doesn't know the difference between the "real" and the "unreal". He doesn't share his name, because he wants only to tell us what he had done. Or maybe he remembers that night when he committed a murder and tries to convince himself of being in his right mind.
But the reader can understand that he is crazy, based on his behavior, speech and thoughts. We can’t trust him, because he tries to show things in the most favourable light. We must draw conclusions ourselves.
However, he believed and believes that he is and was perfectly sane. He thinks that it is normally to kill someone, because something makes you feel uncomfortable and irritates you. He can’t even suppose that he is crazy and proves to us that he is in his right mind. Of course, we can assume that he is sane. But can a normal person say, that he felt pleasure in murder? I think, NO… But our narrator felt: "I could scarcely contain my feelings of triumph. To think that there I was, opening the door, little by little, and he not even to dream of my secret deeds or thoughts."
He is a narrator and one of the characters at the same time. So we can say, that he is a dynamic character. There are given indirect (for example, how he watched the old man eight nights) and speech characteristics ("NERVOUS--very, very dreadfully nervous I had been and am!")

The next character is the old man. We can look at him through the eyes of the narrator. But, as it was mentioned, we can’t trust the main character. The old man had a blue eye, which irritated and scared the narrator: “One of his eyes resembled that of a vulture--a pale blue eye, with a film over it. Whenever it fell upon me, my blood ran cold…”. We can suppose that he was reach enough (the narrator showed the old man's "treasures" to the police), and he was afraid of robbers (“…for the shutters were close fastened, through fear of robbers…”). But we can say, that he trusted the narrator, because he didn’t lock his bedroom’s door. The old man was incapable of defending himself: “His fears had been ever since growing upon him. He had been trying to fancy them causeless, but could not. He had been saying to himself: "It is nothing but the wind in the chimney--it is only a mouse crossing the floor," or "it is merely a cricket which has made a single chirp." Yes, he had been trying to comfort himself with these suppositions; but he had found all in vain.” He was in need of protection.

 

The three policemen don't really have any characteristics. But they play a major role in driving the plot of the narrator's story. The three policemen are fairly unambiguous, flat characters who do exactly what they are supposed to do.

The neighbor plays a small but important role in the narrator's story. Through the neighbor it is expressed narrator’s fear that someone can hear the perpetration of a crime.