You know how when you write and you think you know where the story is going, but then suddenly, it changes. The words come tumbling out and you struggle to get them all on paper, or screen, startled at the turn the story has taken. I'm going through that right now with my book. I had it down, I knew what was going to happen, or at least I thought I did. Then, BAM! the characters took over and things went in a totally new direction.
I feel like I'm scrambling to catch up. I'm rethinking earlier parts of the story. Will this change something that I've already written? Do I need to go back and double check it all? How many times do I re-read the story, looking for inconsistencies? I was thrilled as I was writing the new direction, but at the same time I was horrified. Part of my brain was rehashing what had happened early on and trying to determine if the characters could really do this. Of course they can. It's their story after all, I'm just the conduit for getting it out to the world. SIlly brain.
I am constantly amazed at how the writing process changes from one page to the next, and how I go from struggling with what comes next to frantically trying to get the words out before the story gets too far ahead of me.