Jack Reacher is the fiction twin of TV's Jack Bauer. Both men have utter integrity born of inner conviction. Both are deeply patriotic, but their patriotism owes nothing to whoever is currently in charge and everything to an inner moral code. This makes them both outsiders, not the kind of men who will ever be promoted to general but who are excellent at inspiring loyalty in a small-team, and who are incorruptible. Both are rootless, restless: they can't settle into a family life or domestic relationship for more than the length of a book or series (useful for filmic adaptations), and both men have personal tragedy in their backgrounds that gives them an air of vulnerability beneath their tough-guy exterior. Perfect.