Lelouch Lamperouge

So. Lelouch has the power of Geass. If you've seen the canon, you know that this means he can give anyone one (and only one) absolute order they have to follow by meeting eyes with them. I would like to request permission to use this on other characters, and if so, to what extent. See, typically, Lelouch will use it to further his own military goals, but he's willing to order people to kill themselves in certain cases. Obviously, this something of a game-changer, which is why I would appreciate knowing who can and can't be affected and planning around that.