A good interview question leads to insightful and interesting answers from the subject. The question should give the subject an opportunity to explain the way they think, or challenge their views on a particular topic, for example.
In the novel, Jack represents the inherent savage and violent nature of man. He stands in contrast to the more moral and civilized Ralph. As the story goes on, Jack turns to increasingly violent and savage methods to assert power and control. I believe it would be interesting to ask Jack and Roger questions that would cause them to reflect upon, and explain, their violent philosophy and actions.
Here are some interesting questions you might be able to ask Jack and Roger:
1. Why do you think you deserved to lead the boys instead of Ralph?
2. How do you justify your violent actions on the island?
3. Would you do anything differently if you had the chance?