in SW they complete each other perfectly - Luke with save-them-all--at-any-cost attitude (suicidal most of the times), Han with I-don't-care-(except I totally do)-machismo and Leia with her political practicality in between, balancing them against each other precisely. they get much more one-dimensional on their own - Luke's too saintly, Han's too stereotypically and Leia's too bossy. but together? they work oh so good.

(by the way, have you read three weeks after the end of the world (and counting) (http://community.livejournal.com/skywalkathon/2937.html)? it's SW apocalyfic by penknife, and it nails this relationship between them spot on)