I had forgotten so many details about it.
This is definitely a movie to watch multiple times, knowing how it ends allows you to catch lots of hints in the dialogue. Given that everything that Tyler says are things that Tyler knows!
Details about how he can't be in the same room with Tyler and Marla. He has to decide which personality he uses to interact with Marla on her presence! Knowing this, it shows how there are no interactions from both simultaneously to nobody else. It's always one driving the scene and the other personality with an observer role.
Now that I'm older, I understand the drive behind the character of Edward Norton. He's sick with his life and blames the system for it. The work trip he takes at the beginning of the movie is the moment where he decides to sabotage his life in order to bring out the master of Chaos he didn't know he had inside.
Something that I found very interesting is that throughout the first phase of the movie, where he is going to all the support groups and using different names, it became evident that we never knew his name. Nobody ever refers to Edward Norton by his full name, nobody calls him Tyler until the final revelation.
Had me curious and paying attention to the credits to see how he was presented, and his character is called "The narrator".