Human Puzzle
It's not rocket science. It's not an exact science either. It's human nature observed. They say no one can be a master of it. One has to be the consumate student of it.

Bits and pieces here and there, you notice certain things. It's in how a person conducts themselves, body language, a nervous tick, a stammer in their voice, the timing of how they do things. If they're people who have a set MO, that tells a lot as well. You'd be amazed at how much a person can give away by what they both say and don't say. Even more you tell what is the truth and what is a lie (or what is construed to be cognitive dissonance). Every person has a pattern of these things. They hold a wealth of information if you see it often enough.

To me, each of these observations is a puzzle piece into a person's character. Although one piece doesn't tell you too terribly much, you get a clearer picture with additional pieces. You don't have to get all of the pieces in order to view the entire picture, either. You need to just have enough to get a jist of what that picture is.

I'm an observer and an analyst.