Here’s an interesting article about experiencing your character as being autonomous. I’ve had this happen in brief flashes, when the character seems to rebel against an action or wants to take an action. For some reason the idea appeals to me and I’d like it to happen more often.
Does this happen in your writing?
“The Illusion of Independent Agency: Do Adult Fiction Writers Experience Their Characters as Having Minds of Their Own?”
https://journals.sagepub.com/doi/10.2190/FTG3-Q9T0-7U26-5Q5X
I do, all the time!
I even touched on it in a blog post, https://allaboutleeth.blogspot.com/2016/10/where-ideas-come-from.html, where I wrote:
One clue was a fascinating documentary some years ago which mentioned an (Italian? French?) researcher’s idea that the same mechanism the brain uses to form dreams is at the root of our consciousness itself, and our thought processes.
Another clue is our ability to create mental models of other people - what they’re thinking, how they’ll react, how they’re feeling - and the discovery of mirror neurones, that let us experience the pain or joy of other people, as if whatever is happening to them is also happening to us. That all ties up with our ability to form social groups, and through that, to survive. The evolutionary pressure that drove that development is very clear. So our ability to construct models of other people, good enough to allow us to hold imaginary conversations with them, is another large piece of the puzzle: we really are very adept at creating hypothetical situations, populating them with imaginary or “real” people, and then letting them act and react with each other in our minds. That’s a big part of the answer.
So according to my idea, more empathetic people should have this happen more often.
It certainly happens with me! Not always successfully, I might add.
In the past I sort of resisted the idea. I have no idea why, except maybe it sounded unreal? Didn’t sound creative? Anyway, thanks for your reply. I like what you mentioned about dreams. I’m going to try experimenting with the idea and see where it leads.
This is very interesting and fascinating. It has happened to me. My lead character sprung the ring on his love interest without my permission. 
I was as surprised as she was!
My characters do their own thing all the time. Sometimes, I’m the last one to find out about it.