Frame Story
First, let's make an observation. The title of the book is Tales of the Madman Underground. Notice how "tales" is plural? That's our first clue that the style is going to be just a little different from what we usually expect when we pick up a novel. And indeed, it is. Really, this book is what's known by fancy literary folks as a frame story, or a larger story that contains smaller stories that are unveiled throughout the plot.
Sure, Karl's story is the central narrative in this sucker. But, what about all the side stories Karl tells about how he got his Madman nickname, how he ended up in Gratz's lit class, and how the Madmen got revenge on Tierden and Harris? Often, Karl steps out of his main story to tell us these little nuggets, or, in the case of chapter 9, "Don't Be an Asshole Explained in Easy-to-Understand Terms," Karl narrates the story to Marti at McDonald's.
What's the effect of all this? It kind of gives the Madmen their own mythology, giving us the sense that stories will be handed down as long as the therapy group exists. Paul actually comes pretty darn close to saying this when he explains his reasons for deciding not to go through with his plan to be normal: "When Gratz yelled at me, I felt good, because I knew it was going to be Madman f***ing legend, the maddest tale of the Madmen ever, all of us walking out on Gratz" (21.94).
Which gets us thinking—maybe the best way to read this book is around a campfire in the dark. With s'mores, of course. Want more? Check out "What's Up With the Title."