Identify the significance of the narrator

The nameless insomniac protagonist of the book, the Narrator, is a co-creator of Fight Club, along with Tyler Durden. The Narrator works as a recall specialist for the automobile industry, a job he despises. He attends support groups for individuals struggling with terminal diseases, though he is physically healthy. At these meetings he meets Marla Singer, another individual seeking human contact. Like the Narrator, Marla is also faking her illnesses. The Narrator later learns that he and Tyler are actually the same person. Tyler is a persona that the Narrator adopts, unwittingly. As the book progresses, the Narrator and Tyler find themselves at odds with one another, forcing the Narrator to confront his feelings for Marla and to stop Tyler from taking over his life.