I was thinking parent/child would be a better fit, but upon further thinking about it, leader/follower is pretty good. It is also a bit more distributed friendly, in that you can follow a new leader or switch. Where parent/child, master/slave are more locked. It is a bit silly though to change, in that human history has had slavery throughout history and to this day. Better to know about the problems than to overlook them. Also, throughout history, slavery wasn't always on racial lines, it was usually class based or wealth/monarchy based.