One of the key themes in Beowulf is how identity is primarily driven through familial and tribal associations. The custom of wergild played an important role in medieval society and appears in Beowulf multiple times. Wergild was a method which allowed a family to collect payment if one of the members of the family was murdered or killed by accident. In medieval society, dominated by large families and tribes and lacking in a cohesive and impartial judicial system, wergild was a method for financial settlement to avoid wars between those families and tribes.
In Beowulf, the monster Grendel feuds with King Hrothgar as Grendel refuses to pay wergild for the men he kills.
After Beowulf’s father murdered a member of the powerful Wulfing clan, he did not pay the wergild and subsequently faced numerous death threats. King Hrothgar pays the wergild on behalf of Beowulf’s father, which ends the death threats. Because of this act, Beowulf steps up to battle Grendel because he feels the need to repay Hrothgar for the generosity shown to his father.
Following Beowulf’s defeating Grendel, this line between authentic expression and financial agreement becomes blurred. Even though Beowulf only agreed to fight as repayment, Hrothgar feels a sense of devotion to the hero. This is a cause for concern, because Hrothgar already has sons who will claim his inheritance, and the Danes do not want Beowulf laying claim to that inheritance. In the end, Hrothgar states that the adopted son moniker is simply a term of endearment for Beowulf to honor Beowulf's bravery in saving the Danes from Grendel; it is not a legitimate claim to the inheritance.