Beowulf wants to fight Grendel in order to win treasure and, more importantly, fame (which he calls a warrior’s “best bulwark” [l.1389]). Under the ancient Northern European warrior code, a warrior should seek out the most challenging opponents he can find, in order to enhance his own reputation. Hrothgar suggests that Beowulf may have chosen to fight Grendel in order to discharge a debt to him, when he tells the story of paying a large sum of money on Beowulf’s father’s behalf. However, Hrothgar may simply be trying to save face: it is embarrassing for him to depend on Beowulf’s help.
In lines 1700-84, Hrothgar warns Beowulf about the dangers of kingship. He tells Beowulf that he should “not give way to pride” (l.1760), which makes great leaders complacent when they should be watchful for new dangers. On the other hand, Hrothgar goes on to suggest that death and defeat are inevitable, pride or no pride: “death will arrive, / dear warrior, to sweep you away” (ll.1767-8).
Unferth is “sick with envy” (l.502) of Beowulf’s reputation and courage. From a dramatic point of view, Unferth’s challenge gives Beowulf a chance to demonstrate his skill at boasting. Boasting was considered a legitimate way for a warrior to enhance his reputation, and as Beowulf tells the story of his swimming race we learn that the hero is as good at boasting as he is at fighting.
Grendel’s exact nature is left mysterious. We know that he is shaped like a man (“weres wæstmum,” [l.1352]), but so large that it takes four warriors to carry his head. He is a descendant of Cain, the Biblical figure cursed by God for the murder of his brother, and he is also a “mearc-stapa” (l.103), a “border-stepper.” Some readers have argued that Grendel symbolically represents the people displaced—exiled beyond the borders—by the violent crimes of Hrothgar and of Northern warrior society generally. Other readers have suggested that Grendel represents the unknowable threats that lie beyond the borders of human knowledge.
As he lies dying, Beowulf demands to see the treasure he has won from the dragon. He may hope that the wealth he has captured will guarantee his lasting fame. He certainly hopes that this wealth will compensate his people for their loss of their king. However, the poem makes it clear that this hope is ill-founded. The treasure is “tarnished and corroding” (ll.2761-2), and much of it is re-buried with Beowulf.