Conflict and character are the heart of good fiction, and good mystery has both of those in spades.
“I wanted to be a Priest at one point. I was pretty religious. I was an altar boy, and I was good at it. Then, I started meeting girls and I'm like 'You know, maybe I shouldn't be a Priest.'”
“At some point, you can't lift this boulder with just your own strength. And if you find that you need to move bigger and bigger boulders up hills, you will need more and more help.”