The truth is, some days writing a book is a bit like open warfare. You, the author, often have very particular ideas about what you want your characters to do, how you want them to do it, when and so on. You’d think, since you’re the writer, that you were in control. You’d be wrong.
Once characters emerge fully fleshed in the story they often develop a mind of their own. The story will sometimes teeter out of your control as your muse gives it a goddess-like shove in a direction you never intended. And your characters, well, they might have ideas of their own about how to act in a given situation.