In what ways are the lives of the characters and events of the story governed by predestination or fate, and in what ways to the characters exercise free will?

What is the nature of God in the story? Why is God absent from the story?

What makes Zane a good Death?

What makes Zane uniquely qualified to save Luna?

Is Luna's act of selling herself to a demon to learn black magic really a sin? Why or why not?

Why does Zane seem so easily drawn in by Satan?

Is Zane's act of killing his mother when she begs to be released from pain really a sin? Why or why not?

Zane disregards rules when he becomes Death. Is it dangerous or wrong for Zane to substitute his own judgment for the established rules? Why or why not?

Why is Purgatory run by bureaucracy...