I thought the 'demon' might've been another name for a negative vibe inside you. I've always believed most humans have created 'angels' and 'demons' to represent some abstractions, such as 'good' and bad' (respectively). It helps them to understand things better. Nevertheless, this is just an idea I've always had.
I feel I might have a 'strange' vibe. Most people can't be themselves and restrict their words when they're around me. Anyway, it doesn't affect me at all.
So, the demon thing made me curious and I thought you might've experienced the same thing in the past.