A possibly rude question follows. Do you or have you had friendly relations with anyone you recognised was a psychopath? If so how, why?

A high functioning psychopath, sure. I blame people for what they in fact do, not which parts of their brain are active when they do so. My own visceral comprehension of human evil is such that I don't see much tangible practical difference between high functioning instrumentally rational psychopaths and normal particularly high status humans. In fact since the main difference can be that the psychopath has had to become self aware of their own hypocrisy.