Hi P106, I’ve been following your problem here. But at this point I think Debi has given you good advice to call in a Priest. If you truly believe this is a Demon you are way over your head and need assistance. This sounds like a new relationship, maybe moving on would be advisable if he does not seek help. The knife comment is concerning. There is always the possibility he has a physiological problem you do not know about. You mentioned your relationship was fairly recent. Although possessions are real ruling out the physical and psychological possibilities first is best. I can say at your age this is something I would be moving away from.