In the beginning of the book Augustus and Hazel meet in support group. Hazel has a type of lung cancer and later on Augustus has a cigarette in his mouth. Hazel naturally gets mad at him but he says, "It's a metaphor, see: You put the killing thing right between your teeth, but you don't give it the power to do its killing." Which I personally think makes him much more interesting, just by using a smoking and comparing it to something that kills.
