The raven could be seen as a symbol of death or mortality, and the narrator's character is drawn for us through his responses to the raven and what it represents. In the beginning of the poem, the narrator is mourning his lost love, Lenore, and this is when he hears the phantom knock at the door followed by the raven's tapping at his window. The narrator asks the raven to tell him its name, what it is called "on the Night's Plutonian shore" (in the underworld—"Pluto" is another name for Hades), linking the bird to death right away (line 47). Because the narrator has been so caught up in considering his dead beloved, he seems to link the bird to death. Such a link shows us how depressed his state of mind really is.
Further, he is grieving, and he begins to think that the raven is simply repeating a word—nevermore—that he must have learned from his "unhappy master" (63). The narrator is so sad over his loss of Lenore that he projects this sense of loss and tragedy onto others.
Next, he begins to see the bird as "ominous" as death certainly seems to be for him (as it is mysterious and took his love) (71). Then, as he was initially trying to forget his grief by distracting himself with his books, he wonders if perhaps the bird was a gift, sent by God as a way to prompt "nepenthe" or forgetfulness (82). Again, we see his emotions reflected in his response to and interpretation of the bird's meaning and origins.
The narrator hopes that the bird is from God but considers the fact that he might be a "prophet" sent by the devil (85). He desires to know if he will ever be reunited with Lenore in the "distant Aidenn," or heaven (95). When the bird says, "'Nevermore,'" the narrator becomes enraged and orders the bird away; however, the bird does not leave... Ever.
Now that the narrator has been forced to come face to face with mortality—both Lenore's and, by extension, his own—he can never escape this knowledge, and he grieves it, gets angry about it, tries to forget it, and tries to accept it. We get a sense of his nature, of his character, from these responses.