He is interesting, isn’t he? I think a major reason is that he has no diagnosis on paper; he keeps you guessing. As written, he is trapped in his ritual and his own circular logic, so delusional schizophrenia and associated compulsions makes sense. A schizophrenic RO would be difficult to write but not impossible to make charming (my ex remains quite the lady’s man.) Another interpretation to apply, though, is that he’s the king of his domain and it amuses him to make everyone else follow along with his game. A psychopath who is about to get bored.
At least in my mind, the relationship potential there is explosive. First of all, real people with ASPD are some of the most exciting people to date, in the early stages of a relationship (and most games don’t last long enough to track the later fallout which is likely.) I’ve known some people who entered into productive long-term relationships with them, knowing that “love” wasn’t part of the deal. Second, these are characters we’re talking about - and psychopaths are extremely good at fictional relationships. Especially fictional psychopaths.