Yesterday, I read a post on the Insecure Writers Support Group Facebook page about a writer whose villain was writing his own story. His line was going in a direction she didn't originally want so she wasn't sure if she should keep writing or not. She reached out and asked us our thoughts and almost everyone advised to roll with it, see where it takes her.
I find this veering off happens to me to the point where I have to rewrite some scenes (that I skipped ahead to write) just because they don't fit within the story anymore.
You think you understand your characters, but I think if you are writing fiction, sometimes they will surprise you and take you on a journey you didn't expect.
Has this happened to you? In what way?