Repression and the Unconscious Mind
One of the most famous elements of Fight Club is the “twist” ending: the Narrator and Tyler Durden, seemingly two different characters, are actually just two sides of the same person. The narrator, dissatisfied with his dull, consumerist life, gradually and unknowingly imagines Tyler, his alter ego, in order to escape reality: Tyler is the person the Narrator would be if he could get over his own inhibitions (Tyler is confident, daring, aggressive, charming, etc.).