I just wrote about this in r/nospleep https://www.reddit.com/r/nosleep/comments/4hhre9/i_may_have_spoken_to_a_daemon_living_in_my_little/

My wife and I have 3 kids; an 8 year old boy, a 5 year old boy, and a girl who is almost 3. This past weekend our family decided to have campout in the living room. It was a great evening we setup air mattresses, laid out sleeping bags, ordered fantastic pizza, watched the original Superman with Christopher Reeve, and had popcorn. It was a great evening after all of the food and the movie we turned the lights out for bed around 10 pm. My wife was on an air mattress with our two boys and I shared a mattress with our little girl. My wife and boys were out cold within a couple minutes of lights out, but our little girl didn't want to fall a sleep. She was pretty calm at first, we were talking quietly about the day but after about 20 mins she started to roll around on the air mattress. She then started to act kind of crazy and jumping on me and bouncing around. This wasn't out of the norm for her. Our little girl is not a naughty kid, she just has a lot of energy. Yet, as the seconds passed she kept getting crazier and crazier, she started flailing her arms and banging her head on me. Now that I think about it I am really surprised my wife and boys didn't wake up. The behavior was starting to get out of the norm for her, the jumping was normal but the arms and head banging was a bit extreme for a two year old. My wife always says that I use humor to defuse situations and this time wasn't any different, I jokingly said to her "the power of christ compels you" Right after the words left my lips she stopped, went silent and looked right at me. If you are not familiar with the phrase, it is from the movie the Exorcist and I think it is used during real exorcisms to drive demons out of people. After a moment of what seemed like her staring into my soul she said, "Who is the Devil?" I was a bit shocked, we are a religious family but we don't talk about the Devil or Hell with our kids. I just looked at her and didn't know what to say. Before I said anything she followed up with "Why is the Devil bad?" After a pause again due to my shock I finally got something out and said that he made bad choices. She went on to ask, "Where does the devil live?" at this point I was confused/concerned and didn't really want to have my little 2 year old girl filled with Devil facts, so I suggested that we say a prayer and we should go to sleep. She responded with "Should we say a prayer to the Devil?" I told her that we don't pray to the devil and said an Our father and Hail Mary....as I was saying these she put her head on the pillow and fell a sleep.