I've never used a book in that sense before. I have, however, found it effective to study literature and borrow the techniques of the greats. Symbolism and old, deep-rooted principles are some of my favorites. For example, a good half-orc in a fantasy setting, to me, portrays every man's struggle with their bestial nature. Some give in and behave like animals, becoming violent, greedy, lustful, cowardly, etc, some defy it to the point of being incredibly pious, sometimes excessively so, to the point where they're holier than thou, and others kind of give and take from both sides. The thing that makes this struggle best portrayed for a half orc, though, is that the half orc has a whole lot more stigma against him for his race among humans. Orcs are considered evil, dull-witted, craven, brutal, etc, and sometimes they are. But in any case, with any stigma, be it skin color, weight, etc, a person is sometimes forced into these stereotypes and react cruelly... to the cruelty they were shown first.
Right, I'm gonna shut up, but that's an example. I love trying to make characters as interesting as possible, and as someone said earlier, its not hard to make one; in fact, just make a fairly average person(easy to relate to) and then throw in a HUGE difference that kind of sets them off. Like, a holy warrior who does very well in every walk of character, but can have an explosive temper and is highly judgmental, AND gets guilty easily after realizing he's made a mule of himself.