Strangely, of the persons presented in this so far the one I'd least be surprised to find out having psychopathic personality is Takayanagi himself. I don't mean it in a bad way as lacking certain degree of emotions and inhibitions he could still 'choose' to live/act perfectly normal. And it certainly would explain how he can respond so indifferently to provocations while at same time seeing past them. In a strange way it would explain the choice of occupation too...
That aside, I'm a bit surprised to find the author is a woman.