The other thing you maybe able to try is to evict the household and then move them back in. This is a form of resetting the household.
However, this may not stop them from talking to themselves. I don't usually play with supernaturals on. But have observed a fairy. I can't remember her name but she's a townie in Moonlight Falls.
While visiting her she would walk around her house talking with herself and even seemed like she was arguing with herself. It was kind of odd. I figured it was part of being a fairy.
So I'm thinking fairies aren't crazy, they're just unique. *Snicker*
MrsFlynn