Throughout the story

He isn't anymore? He's still got some of the zero in him, after all, so he's not going to be ABLE to feel things like completely normal people do, at least not right away.

Yes, I know most people who don't feel things the way most others do still should know right from wrong, but Lucaon is different even in that aspect, he grew up in a household that treated those beneath them, mainly servants, with contempt, his family was betrayed by a servant so naturally he won't trust them and he's lived a long time as a zero so he probably doesn't remember how one can treat them properly or, just as likely, that he isn't treating them right, even now.