Herebeald and Haethcyn are the sons of King Hrethel and the brothers of Hygelac. In a tragic accident, Haethcyn accidentally kills his brother Herebeald. As a result, King Hrethel retires from public life and eventually dies. Haethcyn is killed in battle.
The fratricide that takes place between Herebeald and Haethcyn reminds us of the story of Cain and Abel, which in turn reminds us of the demon Grendel and his mother. Medieval Scandinavian warfare was full of tribe against tribe, clan against clan, and brother against brother combat, and the story of Herebeald and Haethcyn is only one example of this problem of blood-feuding.