In Clash of Kings, there is a teenager that is traveling with Arya and Yoren, headed toward Castle Black to be made a part of the Night's Watch. The boy is called 'the Bull' because he fashioned a helmet that has a bull's horns on it. He is very skilled as a blacksmith. His real name is Gendry and he ends up having to go with Yoren when his real parentage is discovered. He has royal blood in his veins and as it turns out most of the illegitimate children are disappearing. In order to save him, they've sent him to live and work at Castle Black. At this point in the story, he's not aware of his lineage.
