People are like onions. Why do I say this? Because onions have many different layers to them and so do people. Chances are you will never get to all the layers unless you've known and lived with this person for most of their lives.
People show you the side they want you to see. Sometimes the real self rear its ugly head and the most inconvenient times. People hide the part of them they feel others will judge them for and give a facade of who they really want to be. Everyone has a closet and inside it is locked with ugly secrets and a variety of their personalities that only show up once in a while. A god fearing, well respected pastor could also be a child molester. A simple, calm spirted girl could have killed in the past. It all goes without saying, you can't judge a book by just looking on it but one has to wonder who we really are.
Its hard enough when people ask you to be honest when they themselves are not. Do we as humans really know who we are and what we want? When you think you know a person and then another side, a secret side comes to light it makes you feel like you never knew them at all. You ask yourself, who is this person because you had settled for the self they wanted you to see and turned a blind eye to the person they really are deep down.
Just like an onion, one person has many selves.