Fight Club Theory: Tyler Durden Isn't The Dominant Personality

While Marla also being a figment of the Narrator's imagination would be a neat twist upon a twist, it doesn't quite add up. For starters, Marla has her own apartment filled with various personal belongings. Tyler lived in the abandoned house on Paper Street and didn't own anything, which went along with the film's themes and hinted that he wasn't real. Why would the Narrator pay for an apartment he didn't use? Additionally, when the Narrator shot himself to get rid of Tyler, that would've theoretically gotten rid of Marla, too. But the most obvious piece of evidence that Marla is real is the existence of "Fight Club 2," set 10 years after the events of "Fight Club," where the Narrator continues having a dysfunctional relationship with Marla. 

Even without all of this, Marla being imaginary would puncture some of the more interesting themes of the story. "Fight Club" satirizes fragile conceits of masculinity, with Tyler saying they're a "generation of men raised by women." Marla, as the most prominent female character, flies in the face of this idea. When the audience first meets her, she's by no means a platonic Madonna figure. She's messy and chaotic but still exemplifies certain feminine traits, like wearing a pink tulle dress. 

Marla represents a realistic life the Narrator could have, not fully masculine nor feminine. A life with her would likely be frustrating and anxiety-inducing at times, but that's what life is. The Narrator sought out the fight club to find a way to escape the monotony of life, but that's an ideal that can never be attained. The best he can hope for is to find someone who complements him enough to find a smidge of peace in the randomness that is existence. And for that idea to work, Marla needs to be real.