You mean there is a fine line between malevolent and sociopath.
I'd say he is a border line psychotic with more than a smidgen of malevolent fantasies. Between full moons, his open borders policy allows him to cross an unsecured border to enjoy the fullness of these malevolent fantasies. During full moons he is quite opposite and almost rational except for the twitch.
I hope you understand. Sometimes I find it difficult to express myself. /s