Sempre io, Jack Reacher

Exploring Reacher's past added depth to his character, but I wonder what influenced Lee Child to make this a central theme in this novel.

The story had me on edge at the start and end, but the middle felt a bit slower. I'm curious if that was a deliberate choice to build suspense.

The locations felt very vivid and integral to the story. Did the author base these on real places or create them from imagination?