In the prologue to the story, Donald Miller admits that he specifically addresses men who grew up without a regular father figure. He aims to explain what that means and the effect it has on one's life. He also explores areas that a man without a father must learn on his own, such as women and sex.
Mentoring, according to Miller, fills some of the gaps left by a missing father. Though the idea of a father appeared as foreign to Miller as a fairytale dragon, he learns some of life's lessons through various men that mentored him.
To Own a Dragon: Reflections on Growing up Without a Father