This is when Dean got the mark of Cain. You just find out that your entire life has been a lie when Castile finally decided to tell you who your family actually was after keeping you from the world for years. When you do research you find that you have friends, family, other people like you that will make your life so much more fun. You could be different. You could be yourself. That's what you thought until you learned people are using you to get to other people.
London; a solo hunter that, on a case, ran into the Winchester boys, which leads to a long friendship, and even a relationship with one Sam Winchester. Later Chris comes in too, who ends up being Deans daughter.