I wanted to pass on the classic description of an “unreliable narrator,” which Sarah had dug up. This comes from a foundational work in literary studies, Wayne Booth’s The Rhetoric of Fiction (1961):

Our terminology for this kind of distance in narrators is almost hopelessly inadequate. For lack of better terms, I have called a narrator reliable when he speaks for or acts in accordance with the norms of the work (which is to say, the implied author’s norms), unreliable when he does not. . . [when]the narrator is mistaken, or believes himself to have qualities which the author denies him. …

Unreliable narrators thus differ markedly depending on how far and in what direction they depart from their author’s norms…

…At one extreme we find narrators whose every judgment is suspect. At the other are narrators scarcely distinguishable from the omniscient author. In between lies a confused variety of more-or-less reliable narrators, many of them puzzling mixtures of sound and unsound.