The books `The German Lesson' by Zigfried Lenz, and `Cannery Row' by Steinbeck
As a teenager I read this book about a teenager send to juvi by his duty bound father with fascination. It made it crystal clear that one's duty can easily be perverted. Another book that I read soon afterward that has shown me a different route was `cannery row' by John Steinbeck, where a biologist and a doctor is befriended by riffraff. Of course Catch 22 by Joseph Heller and his complete mockery of duty was not too far behind... My duty nowadays is to those I love, and sometimes even myself...