[csomar]

This sounds similar to Schizophrenia although a medical examination is required. Whether your friend is intelligent or not, hallucinations are a medical issue and they can affect anybody as our understanding of the brain is limited.

I’d start looking for a new accommodation or a way to kick him out. As harsh as this sounds, mental health issues are extremely taxing. I’d not be responsible for anyone like that unless it’s very immediate family members.