To most men his crown is a symbol of power, but to Robb, donning it every morning, it is just a reminder. It reminds him that he chose Roslin over Jeyne. It reminds him of his bastard son growing up in the Crag. It reminds him of Sansa, whose smiles never seemed to reach her eyes. It reminds him of his failures as a son, a brother, a husband and a father. Men might hate him for crowning himself, but none more that he hates himself.
