This is not a book about cancer, although many of the characters have cancer. This is not a book about dying, although there is some deaths. It is a book about defining your life and the choices you make in spite of obstacles in your way. Augustus Waters and Hazel Grace are the hero and heroine and their story is about their choices. 
 The title comes from Julius Caesar, Cassius to Brutus: The fault, dear Brutus, is not in our stars, 
 But in ourselves..." 
 Augustus Waters says: "My thoughts are stars I can't fathom into constellations". He fears oblivion, but Hazel Grace shows him that falling in love is a better choice.