Complex sentence: Disturbed, the narrator calls Marla from his hotel room and discovers that Marla also believes him to be Tyler, who suddenly appears and explains that both he and the narrator are dissociated personalities in the same body.
Split into simpler sentences: Disturbed, the narrator calls Marla from his hotel room and discovers that Marla also believes him to be Tyler. Tyler suddenly appears in his room, and explains that both he and the narrator are dissociated personalities in the same body.