I have come to know that my writing will never - I mean quite literally never - turn out the way I thought it would.
As a rule I am not a planner when it comes the writing (though heaven knows I'm a planner for everything else in my life). I am a pantser. I usually have some idea of what the story is about and where I want it to end up, but I never know what is going to happen along the way.
I find that even when I am sure of how a scene will happen - I am bound to be surprised by the unexpected. My character take over my plot and I feel like I'm follow them around and telling what they are doing. I don't make them do things, I just report what they do. And every now and then they catch me completely off guard.
An unexpected twist, a person interrupts the scene uninvited, the characters say something that they were not originally scripted to say, etc., etc. And yet, when I am interrupted by the unexpected, I find that my story is always more interesting! I get excited to see what's going to happen next! I want to know what my characters are up to when I'm not watching, and why they chose to do something that I had not planned for them to do? Where are we going with this unexpected plot twist?
So I have learned to expect the unexpected in my writing - which then makes the unexpected never happen as I am always expecting it ....
The point it - enjoy and embrace the unexpected in your story! It might take your story away from what you had planned, but it also might take your story to that next level with the depth and intrigue you've been trying to obtain!