Herraud's best friend is Bósi, the younger son of a former viking named Thvari or Bryn-Thvari by Brynhild, a former shieldmaiden and a daughter of King Agnar of Nóatún. (Thvari had formerly partially maimed Brynhild in a duel, whence she was known as Bögu-Brynhild "Stunt-Brynhild", for she never fully recovered. Thvari then married Brynhild, who bore him two sons, Smid ("Smiðr") and Bósi. Smid learned some magic from their foster mother Busla, who was a powerful sorceress.) Bósi is sometimes called Bögu-Bósi after his mother.