My finished books only bear passing resemblance to the novels that come from them . . . Allow yourself to be surprised. Control is seriously overrated. Take this from the person who used to write thirty-page chapters. I was proud of the fact that I could write a story that would have the exact word count called for in the contract.
Life is too short for that sort of nonsense.
If your subconscious mind is taking your character in a new direction . . . You're still the writer. You can stop the process at any time. But if you don't ever let yourself go off on tangents, you'll never discover the amazing secrets you've been hiding from yourself. And your writing will be dry and forced, and you may discover that you have less and less reason to finish each book, because you know there will be no surprises.