Who is Siddin from Wizard's First Rule and what is their importance?

Siddin is a young boy of the Mud People kidnapped by Darken Rahl as a gift for his friend Demmin Nass. For unknown reasons, Siddin is being kept in the dungeon of Queen Milena's castle where Richard and Kahlan rescue him. Eventually they are able to take him back to his village riding on a red dragon.