We're watching Heroes. I've never followed it, but the dh mentioned how one character who used to be bad is suddenly good. And I'm thinking of how sometimes there's a revision of character history or personality partway through a tv series or novel (more commonly in a tv series, as that's rolled out episode by episode, not all the chapters at once as in a novel).
I was thinking of how important it is to establish trust when you're going to make some twist. That is, the reader/viewer has to believe that this isn't just a screw-up, that she shouldn't turn off the TV or throw the book against the wall, but rather hold on, keep reading/watching, to find out how this works out.
So how do you establish that kind of trust? How do you get the reader to believing that you will in fact resolve this satisfactorily?
(Now I'm thinking that the even harder task would be keeping the reader reading withOUT trust-- thinking you've done something crazy, jumped the shark, betrayed the great traditions of Western fiction, etc.-- but your voice or antic plotting or characterization or SOMETHING is just so good, she keeps reading, and the perfect ending, the intricate but perfect resolution, is that much more exciting and satisfying because she doubted you. :)