You don't know someones character. Because there is no absolute line between good bad right wrong or any distinctions you can draw from their behavior. The human mind is about infinitely complex and there's always a deeper understanding to a human beings feelings that drove them to do whatever they do. Really any method of "how to read a person" that you'll ever hear is oversimplified and not entirely accurate. You just have to draw your own lines and figure them out from your own experience. It may help to smoke weed or drink with them occasionally. Odd as it sounds, marijuana opens up empathetic centers of your brain and helps you emotionally get on someones level. Whereas alcohol lowers their inhibitions and you're likely to see how they are without any moral restraint holding them back.