Person goes mute and the private talks for them, or more like an evil dummy playing with a ventriloquist? I could imagine one where the private catcalls women to get the protagonist slapped or laid.
I advise you open a story and start writing. Even if you don't get it to a quality that you want to release it. You will at least get out of the loop and start thinking about the next thing. In my head I can say xyz is the plot but I didn't realize that there was much to talk about a. I might have a cool scene but it can be hard to think of how I would get there until I write it down. Someone might see your idea and use it but I wouldn't hold my breath. If you are going to release the story make sure you use a program that checks your grammar. They aren't perfect and require a bit of knowledge on your part. Often I have them tell me that a word is complicated but it is better than the word they are suggesting. It wants to turn "summon" into "send for" or "call" which doesn't make much sense for summoning a demon. I would also keep your chapters above 500 words long for most story's. I aim for 1000 since mine are entirely linear stories although sometimes it makes sense to end a chapter sooner.
