The narrator in Edgar Allan Poe's short story The Fall of the House of Usher serves, as narrators always do, the important role of observer. In Poe's story, however, the narrator's role is magnified by virtue of his relationship to Roderick Usher. The two were childhood friends, but had not communicated in many years, probably since childhood or, perhaps, young adulthood. The narrator admits to a certain gap in his level of knowledge of Roderick, noting, for instance, that the latter's "reserve had been always excessive and habitual." The years, however, have not relieved the narrator of his concern for and curiosity about the Usher family and, having received Roderick's plea for his friend to visit, hastens to the Usher estate.
As Poe's story progresses, the narrator and Roderick spend many days together, the former endeavoring to raise the latter's spirits while Roderick mourns his imminent doom and that of his sister Madeline, whose mysterious illness is characterized by death-like states that lead the narrator to believe Roderick's conclusion that Madeline has died. The interactions of the narrator and Roderick throughout, however, seem to exist solely for the purpose of providing a witness to Roderick's continued descent into insanity, and to the horrific developments pertaining to Madeline who, of course, is not dead when entombed by the two men -- a fact known to Roderick and belatedly discovered, to his horror, by the narrator.
The events described in The Fall of the House of Usher are, needless to say, horrific and melancholy. But for the presence of the narrator as an active participant in the final days of the Usher family, there would be no record of the events described, and that is the principal role of this third character in the story. He exists to serve as witness to Roderick's final days and to the horrors that befall Madeline. Only as an old and trusted friend of Roderick's, however, has he been permitted this vantage point. The character of Roderick needs a friend or accomplice with whom to spend time reading the stories that figure prominently in Poe's narrative, especially The Haunted Palace, the verses of which occupy an inordinate amount of space in the story. The final verse of that ballad are particularly relevant for the broader tale:
And travellers now within that valley,
Through the red-litten windows see
Vast forms that move fantastically
To a discordant melody;
The narrator is the traveler who has crossed a great deal of land to be with this childhood friend whom he confesses to barely really know. The narrator is more than a mere observer; he and he alone can survive to document the final days of this depressing clan and its crumbling estate.