Look to make your course regular, that men may know beforehand what they may expect. — Francis Bacon
You treat other people like you expect to be treated. Sure, its a Golden Rule kind of thing but that isnt the point here. While other people treat others differently than they expect to be treated and treat some people one-way and others another, you generally have one set of behaviors and attitudes that you use in most all interpersonal situations. Your consistent style with people has one important benefit. It lets you gage conformity and variation in the behavior and attitudes of other people and of specific individuals at different times. This is in part why you are so good at reading people. You are the constant in the reading people equation, while other people are the variables.