Autisneed help for autistic family friend

Hello everyone, I have come on site because I have a close family friend who I am very close too and he is very close to my family due to mother babysitting him when he very young.

He has Asperger's Syndrome and two personality. Now he doesn't show 2nd personality when around people, he only show it when he alone. But, I started believe it may be something different. So when I ask him about it he deny it many times, but I eventually get him to open up about it and he tell me about it, but he tell me it is a demonic personality and that it couldn't speak to me, only to him. He took medication for long time for this issue when he was younger but now that he about be 38, neither I nor mother see it in him for least 8 year now, but i guess he just hide it better.

My question is as follows.

Can a personality excluded from a person base personality become sentient? If a person suffer long enough from chronic lonliness and isolation like he do, can a 2nd personality become sentient?

Now this why I say previously it weird to me. I go in his room 4 night ago to check on him to see if he sleep because many time he stay up playing game all night and I try make sure he sleep well and better but I notice he talk in his sleep. But I notice he talk normal, but then a deeper voice like loud whisper answer back very slow, almost like evil character from a movie but it all from his mouth, because of what I do for living back home in beijing, it require me to know many languages. He speak normal but voice that reply to him is clearly in hebrew.

I tell this to his father and sister and he not believe me, in fact he laugh, but when I urge him this happened, he get mad, so I go and see him again last night and he do it again so I record audio with my phone and I able hear his voice on my phone but not other voice I clearly hear from across his room, and i sit in chair next to his bed when I record it.

I told his dr. in a call today, but he even not believe me. I myself have very different view of demons because in my culture they have good and bad demons but I know in western culture they all bad.

I don't know what to do, his father doesn't believe me, his dr. doesnt, he doesn't reveal his other personality to his dr. and is very good at hiding it.

On top of that untill few year ago he always very positive, but now, I notice he get very graphic with comments he makes online towards the human race, what I mean is for example when he hear about racial or political violence he posts comments like " And this is why the human race deserve be burned alive" I see many comment he make saying he want join demons in torturing certin people like J Trump, and search history very disturbing, he search anciant scriptures of witch rituals and demonic contracts with demons and devils.

Many searches are about how to sell his sould for friends or a girlfriend or how to sign a contract with the devil through blood in exchange for friends even if he die in 1 year.

I think he so desperate for friends that he is willing to deal with demonic contracts, even in my culture there is a long history with contracts, so this I do believe is possible but unbelievably difficuly to navigate. I told him that I tried to record his talking in his sleep and he actually not mad, he just told me don't do that because I might anger him, I asked him anger who? then he just replied with "you've been warned"

I just don't know what to do, everything I have seen and heard him do, I have told his dr. and he has brushed anything to do with religious happenings or anything away. He says he doesn't believe its a concern because when he speaks to him its like he doesn't show signs at all or any 2nd personality. I looked at his computer today and search history gone.