I hope you read the Last Arkham, his first app arc in Shadow. He's supposed to be very smart & charming....he charmed and warped Jeremiah Arkham's mind. Sadistic (as a motivation) might be out of character for him since he dedicated himself to "liberating" others ("zombies") from their pointless existence (though that has not stopped him from making bloody messes of his victims). (I tend to think he might be sadistic, but doesn't quite realize it or own up to it)