Both dwarf backstories contain events that you hear about during the course of the regular game. If you play as a commoner, you kill a major crime boss and set up Jarvia to take over. If you play as a noble, you are the king's second child, the one who was banished for supposedly murdering you elder brother. I liked them both a lot. One neat thing is the different spin they put on Orzammar politics: from the commoner's point of view, Bhalen looks like a good man and potential champion for the poor (not to mention, he's keeping your sister as a well-loved mistress); if you're the noble, he's the scheming little bastard who set you up and screwed you over. And, of course, it's entirely possible for both these things to be true. Which is another thing I loved about the game: all the moral ambiguity. There is right and wrong, but sometimes it's hard to tell which is which.