family is family. it's normal to be an ass to everyone but your family. Hell, the Zoalords have shown plenty of contempt for humans and everything else, but most of them have at least one redeeming quality. Even Guyot shows respect and concern for the loss of some of his men (he cryed out Panodyne name as the latter died trying to protect him!) though deep down he doesn't care for them at least he shows he values them unlike Kahn. Barcus has been one of the biggest monsters in the series towards humans, but a true friend and devoted follower to his own Zoalords.