What inspired this question for me was reading Alex Haley’s “Roots” after having just read “Beloved” by Toni Morrison. I thought that the two taken together give a wonderfully detailed image of American slavery and it’s effects on the body (Roots) as well as on the soul (Beloved).
Another that came to mind was Jack Kerouac’s “On The Road” and Hunter S Thompson’s “Fear and Loathing in Las Vegas” as I personally felt that FaL was written as a direct parody and skewering of the kind of transcendentalist optimism we see in someone like Kerouac.
I guess I’m thinking of books that look at similar issues from complimentary angles or books that seem heavily inspired by others and almost responding or expounding, so that you come away having learned more than the sum of their parts.
EDIT: Doesn’t have to be all fiction. Non-fiction is welcome as well.
Albert Camus’ The outsider (or, The stranger, depending on the translation) and A happy death.
One can throw in The plague and Reflections on guillotine for good measure. The former helps you understand Camus’ way of writing while the later helps you realize his beliefs regarding death penalty.