One of the things I've been thinking about recently is character and plot. Specifically, in the sense of having a protagonist who does what a protagonist is supposed to do in traditional story construction - a person or persons facing a dilemma they have to overcome by dint of their own efforts.
My first novel, Touched by an Angel, didn't sell. I wrote it in six months in, I think 1997, when I had just finished a college course and was waiting around to see if I could get some kind of a job. The book did get me an agent, though, the same agent who recently secured me my two-book deal. It was good enough in that sense. So why didn't a publisher take it? Primarily because the main character was swept along by events. Things happened to her, rather than because of her. In the best situation, a book ends when the main character brings that ending about through their actions, whether that ending is a good thing for that character or not, is another matter altogether.
On the other hand, look at the first Indiana Jones movie. In that, Indy is trying to get to various artefacts before the Nazis do, and spends much of the story chasing around after the same things, occasionally beating the bad guys. But at the end, on the island where the big ceremony takes place and Indy and his girlfriend have sneaked along on a Nazi sub (if I recall), they are captured and tied up. They keep their eyes shut while the ceremony takes place, and all the Nazis are torn apart by demons emerging from the Ark.
Now, that movie is rightly regarded as a classic. But if you think about the ending for a second, the Nazis aren't defeated because of Indy's actions. They're defeated by something beyond the grave, and Indy is effectively a spectator. This isn't in any way to imply it's an unsatisfactory ending, it isn't. But it's the kind of thing I've been thinking about a lot recently, since I'm at the three-quarters mark with Against Gravity. My protagonist is at a certain point, and rather than being an observer of the ending of the book, I want him to be an active and important participant. Otherwise, why write about him at all? But I've been thinking, he doesn't necessarily have to be responsible for exactly how the ending comes about (thought it might be preferable, in terms of plot satisfaction), as long as he does have some influence over it.
But this is the one thing I've come to realise I find the hardest when I'm writing. Plot, no big problem. Writing the prose, no big deal. But combining the two in such a way that my protagonist(s) have an active part in how the plot actually develops? Now that I find difficult.