In the first scene when the narrator is talking about his insomnia there is a single frame of Tyler Durden on the screen simulating the beginning of the protagonist’s decent into what will soon be a full blown confusion between the narrators perception of reality and an alter ego that he creates. Most of the viewers may not catch this the first time, as if it was subliminal messaging. It is as if the director is giving the viewer a taste of the distortion of reality that will only intensify as the film progresses.
David Fincher portrays the protagonist as the narrator, yet leaves him without a true identity, a “single serving friend” so to speak. The narrator takes on several alter egos and identities while attending a variety of help groups for the dying. The director is showing that the protagonist is looking for any escape for he own pain, and the reality he is part of, hence of the creation of Tyler Durden.