Mr. Durden

There are three main characters in this novel, the narrator, Tyler Durden and Marla Singer.
I have already talked about Marla; now I'm going to talk about the narrator/ Tyler Durden.
Wait... What? Why did I used a slash instead of an "and"?

Throughout the book the author gives you a lot of hints, but you really get it at the end of it; and if you were wondering, yeah, they are the same person. Our narrator has de dissociative identity disorder, also known as multiple personality disorder.

In one hand the narrator of the story is a normal guy with a normal job in an insurance agency, what a boring life you'll think. He suffers insomnia so he has to go every night to a support group so he can let out all his feelings.
Then Tyler, how can I even start to describe him? He works as a waiter, were he harms indirectly the clients; as a projectionist, were he puts obscene images; and he also does his own soap, he gets the fat from stealing liposuction clinics.  What kind f person does that? I know, he is extremely weird. He's house has the barely sufficient to survive, his philosophy rejects consumerism and he thinks disaster is a natural part of his own evolution.
"We made soap out of her. Her. Marla's mother"

This characters "meet" in an airplane; the narrator was returning home from a bussiness trip, Tyler was just there. When the narrator arrives to the airport he is notified that his suitcase was vibrating so it has to be checked by security, by the time he arrives home he sees that his apartment exploded. So he decides to call Tyler.

During the whole novel the narrator repeats a lot this phrase: "I know this because Tyler knows this", this is one of many hints Palahniuk wrote, although it doesn't makes sense till the last pages.