Wow, I was right. Xasthur is some demoness from the Necronomicon plus mixed with a name of a Santeria spirit. The guy must be into some crazy stuff.
It's funny how musicians, specially black metal, have a way of relating to the spirits on a totally intuitive, musical way. That is, those who do not practice occult rites, that I know of examples being Yamatu, Therion, Mystifier, Emperor, Mayhem, Beherit, Acheron, Demonic Christ, Black Funeral, Dissection, Sovereign, Profanatica, Arckanum, Morbid Angel and many others. Glen Benton also claimed he was possessed, but I guess it's more of a joke, with a real backstory which is subconscious influence. They even mention the necronomicon on one of their lyrics. A lot of those are influenced by HP Lovecraft also.
I never really listened to xasthur until now, I am enjoying all of his work. Pure ambiance and sadness, no matter what this guy does, ambient soundtrack metal or whatever, it's his emotions on music he wants to convey and I find it all in very good taste. His persona seems similar to that of the man of Krieg.
I don't really think he does not talk to people. I think in reality he hangs out with people