One example would be the problem of evil and suffering that plagues Ollie in my novel Deception. Of course, I didn’t resolve that problem, and none of us will, but I had to really ponder it, and think of it in terms of the confusion and anger it might instill in someone like Ollie. Why did his wife die? Why did someone else close to him die? (Not saying who to avoid spoiling the story.) Why do the bad guys sometimes get away with it, and why do the good guys sometimes suffer and die?  Ollie’s road to alcoholism and cynicism was paved by the pain of loss he was trying to mask.