The Barbarian is a warrior who is found in the forest near Fleur de Lys, presumably there to find and kill Sordid. He claims to have the courage of a bear, and likes robbing from the rich. He is also an apprentice accountant (that's why he keeps everything he steals from the rich).
When Simon first meets him he has a thorn stuck in his foot, which Simon removes. After resting from the shock, he then gives Simon a whistle to blow if he is ever in danger. Simon doesn't have the strength to make any noise with the whistle (as it has something stuck inside) but when the Troll blows it the Barbarian appears. He throws the Troll into the river and bounds away.