Kjartan, Bolli, and Guðrún's fatal triangle
Kjartan Ólafsson and his foster-brother Bolli Þorleiksson grow up inseparable. Kjartan asks Guðrún Ósvífrsdóttir to wait three years while he goes abroad. Bolli comes home first, tells Guðrún that Kjartan is courting the Norwegian king's sister Ingibjörg, and marries Guðrún himself. After years of escalating insult, including the theft of Kjartan's wife Hrefna's headdress, Guðrún pushes Bolli to join the ambush in which he kills Kjartan, who dies in his arms; Kjartan's kin later kill Bolli in revenge.
