How open minded is John? Maybe you should tell him about your past experiences, and what you witnessed at their house. He may be skeptical, but hopefully he will recognize that you wouldn't make up this sort of thing.

Do you have pictures of your past bruises to share with him? That might help. Right now, it will be better for Chris if he has a support group.

I wish I knew more about how to help. The only ideas I can cone up with are: have someone sleep in his room with him and find out all the various types of house blessings/cleansings you can get.

I rented a house with three others, for awhile. One girl had a similar visitor (not consistently, but she never shared her other stories). One night she was so terrified, because he was by the door. She called me on my phone, and I rushed to her room. By myself, I am a scaredy cat, but when I am in protector mode, there is no time for me to care about fear. Yay adrenaline. Anyway, we slept with the light on, I put a religious picture above the door (I have this superstition about thresholds), and we prayed.

Every culture, belief system, has their own way of dealing with these sort of situations, as well as ideas about demons. Regrettebly, I am not as well versed in all of them, but all I can share is what I have been taught. Take it or leave it, up to you. When around this entity, stay as calm as possible. Try not to show fear, but don't get really angry and piss him off, either. Don't use a Ouiji board. Fill the house with positive energy, regardless of how much negativity the entity tries to instigate, don't give him that power. Otherwise, seek outside study and help from those who might be able to chase him away. Those are things that I have tried.

I am so sorry, my advice is threadbare, and probably sucks. I hope your family is okay.