The best literary agents are also talented editors. They can instruct and guide an author toward writing a better book. So when those agents talk about writing, it's wise to listen. Veteran agent Donald Maass gives advice for writers in his book The Fire in Fiction: Passion, Purpose and Techniques to Make Your Novel Great, and you can read an excerpt on character-building here. Maass mentions something children's writers often overlook: the impact of greatness, either by the protagonist, or on the protagonist by another character. Children are drawn to greatness and want to see heroes in their books. Infusing ordinary, flawed characters with moments of greatness makes them immortal. And immortality is what every writer dreams of.