The famous reveal—that the Narrator and Tyler are the same person—changes the reading of every scene. The self-loathing isn't metaphorical; it's literal. When the Narrator beats himself up in his boss’s office to blackmail him, he is finally taking action. But it is violent, self-destructive action.
That "something" arrives in the form of Tyler Durden, his chaotic, soap-making doppelgänger. Here lies the core of the Narrator’s tragedy: he creates the man he wishes he could be.
The Narrator is the superego—the rule-follower who flinches at conflict. Tyler is the id—the anarchist who pisses in soup. But note: Tyler doesn't exist without the Narrator’s repressed rage. When the Narrator goes to support groups for diseases he doesn't have just to cry, Tyler turns that emotional vulnerability into a manifesto of destruction.