Good as a book may be, what always pisses me off is the previsible ends. As I read the 4th or 5th book of Harry Potter (can't remember) I put down the book at the end and immediately told myself "Last Book=Harry vs voldemort=voldemort dies, no plot twists". Or (Please don't spoil it for me, still reading it) Inheritance (which I repeat I AM AT THE PART WHERE HE GOES TO VROENGARD, SO DONT SPOIL IT!), where I can pretty much see that Galbatorix will own Eragon, but Murtagh will kill Galbatorix and redeem himself as he dies. (Return of the Jedi, anyone?) It's mostly like this in Adventure/Fantasy genres, so predictable. Well, enough talking, my question was: "How do you make a non predictable story end without having a secondary character who you see once in the novel kill the bad guy?"