I grew up in Spanish language congregations where demon stories were more common than in English language congregations. It was part of the culture. In Mexico everyone seemed to have a ghost story to share, so these people (like my parents) brought this with them and adapted the stories to fit with JW doctrine.
In my family there was a reoccurring pattern. My parents were in a loveless marriage and every now and then there would be a huge blowup. Eventually things would settle down, my parents would make up, and there would be a cleansing ritual where we would purge our house of anything that might be associated with demons because surely the demons were making my parents fight. It wasn't that they were mismatched and should have never gotten married in the first place.
Most of these stories are benign and kind of comical in retrospect. But every now and then it veered into dangerous territory. There was a very troubled family that was kind of on the periphery of the congregation. They were off-and-on inactive. Their youngest son was clearly troubled. He just had that look to him. One day the elders get called to their house because the son is becoming violent (he was in his teens) and was mumbling gibberish. The kid confesses to hearing voices in his head telling him to kill his mother. The elders, of course, recommend prayer and helped them search the house for possessions that might be associated with demons.
I know this because I was told this story first hand by one of the elders who was there to counsel them. He was a high school drop out and a welder. The other elder was a barely-literate man whose education consisted of a few years of elementary school in Mexico. Instead of receiving professional medical assistance, this dangerous teen was receiving counseling from these two guys.
I don't know what happened to that family. This incident happend about 20 years ago. I've always wondered. Not long after that, I moved away and know very little about the goings on of my old congregation anymore.