Impartiality and even handedness in any social environment is an unreachable Utopian ideal even with the best of intentions. When it comes to roleplayig, some players will be favored over others in various ways and for various reasons. That is just how it is. I have been on both ends of this as a player and have been guilty of it as a GM as well. So you simply have to accept it as a fact of gaming life and life in general.