Don't Ever Get Old

The tone shifts between dark and funny in ways that feel so natural. I'm curious whether this was planned from the start or evolved during writing.

His actions are often morally ambiguous, which made me wonder how much sympathy I should feel. What did others think about his sense of justice?

The ending felt both satisfying and unexpected, which is rare in crime novels. Did it catch anyone else off guard or was it foreshadowed?