When someone first reads one of my books, the first thing I usually hear is how they loved the plot twists. My books are full of them, as much as I can manage. I dislike cliche or formula plots where everything of the plot is easy to see coming. I'd like to claim great brilliance in crafting the twists and turns in my books, that I carefully craft each one, knitting it skillfully through each scene. The truth is much less romantic.
My characters do it. I must confess, they deserve pretty much all the credit. I show them where things start (sometimes they convince me my first starting point is wrong, I always listen to them) and tell them the ending result and a few key points in between. How they get to those points, and what they do with those points, is all up to them.
It's true, I have very little to do with the twists and turns that happen in my books beyond creating the characters. I dabble in psychology, finding the human mind fascinating. I'm also a very empathetic person. I can see a person's point of view on anything, even if I don't agree with it at all, including fictional characters. This, I'm convinced, is partly why my characters get so deeply formed. And from that, I turn them loose and watch the magic happen.
The rest of the story is a cause and effect ride, and my characters rarely react to things quite the way I plan or hope or even like, or do anything easy, yet they react completely true to themselves. I learned early on that attempting to force one of my characters to walk a planned outline ends in the death of my muse. Some of my characters are even more stubborn than I am.
I sometimes do have revelations about a character deep into the middle of a story, and then go back to weave hints or supporting things into earlier chapters, and strengthen it all when I work through the rewrites. Sometimes whole new scenes pop up, sometimes whole new supporting characters, but it all branches from the characters themselves.
I do work hard to make sure it all works well together. I'm sure I miss some things, but I do my best to make sure ends are tied up (never in a very expected way), and that they make sense.
The other thing I work hard to do is showing readers who my characters are and how emotional each decision they have to make is, along with the settings, but those are two subjects I'll write about at another time.
Till then, I'm again happily creating more characters to work out a new plot...