Now, the title isn't meant to imply that I have no control over my characters. I do. But sometimes, as I'm writing a scene, I realize that how I initially thought my characters would react to a certain situation (or comment) isn't correct. And sometimes - just sometimes - their reactions surprise me.
I don't know if I'm the only person that this happens to. I very well may be. I also very well may be crazy - but we're not going to get into that.
What we are going to get into is characterization. Yes, you need to have control over what's happening in your book - you're not a very good author if you don't - but you also need to know your characters. If you force them to react in a way that isn't natural for them, it's not going to make for very good writing. If you find that you're doing this a lot, write a new book or create new characters, because your story and characters aren't matching up.
So how do you know if something's a natural response or not? Well, one easy way to test it is to have other writers read it. When you're reading someone else's book, it's easy for you to see when the characters aren't reacting naturally. Let others point out things in your novel that may be forced. Another way is to read other books/watch movies that have characters similar to your own, and see how they react to similar situations (this is NOT to be taken as gospel - every story has different circumstances! Somehow, however, drawing comparisons helps).
Me, I have a slightly different approach. I am heavily involved in theatre, and my work as an actress and director has always been character-focused (which I believe is the only way to act). I delve completely into that character's mind and personality when I'm preparing to perform in a play. When I'm writing, I do the same things I would do when acting - I hold "interviews" with my characters, ask them different questions, then put myself in their shoes and give the answers.
Yes, all the thoughts (questions and answers) are coming from me. But sometimes the characters surprise me.
I still need others to look at my work (for goodness sake, of course!) but for me, it's relatively easy to get inside the mind of a character. And you can't force your character to be something they're not.
So a slightly scatter-brained post, but that's what you get when you're neck-deep in finals and suddenly two of your characters decide to kiss (which you did not foresee happening at that point in the novel).
Have your characters ever surprised you?