Grendel’s relation to Cain has been mentioned at several points in the story and is revisited here. Having Cain for an ancestor is obviously a liability from the perspective of a culture obsessed with family loyalty. Grendel’s lineage is therefore in many ways an unnatural one, demonic and accursed, since Cain brought murder, specifically murder of kin, into the world. As discussed earlier, it is possible to interpret Grendel and his mother, considering the unnaturalness of their existence, as the manifestation of some sort of psychological tension about the conquering and killing that dominate the Danish and the Geatish societies. Certainly, the humans’ feud with the monsters seems to stand outside the normal culture of warfare and seems to carry a suggestion of moral and spiritual importance.

The question of Grendel’s lineage is one of many examples of the Beowulf poet’s struggle to resolve the tension between his own Christian worldview and the obviously pagan origins of his narrative. The narrative’s origins lie in a pagan past, but by the time the poem was written down (sometime around 700 a.d.), almost all of the Anglo-Saxons had been converted to Christianity. The Scandinavian settings and characters thus would have been distant ancestral memories for the inhabitants of England, as the migrations from Scandinavia and Germany had taken place centuries earlier. Throughout the epic, the poet makes references to this point and tries to reconcile the behavior of his characters with a Christian system of belief that often seems alien to the action of the poem. Early on, for example, he condemns the Danes’ journeys to pagan shrines, where they make offerings, hoping to rid themselves of Grendel. Additionally, Beowulf’s heroic exploits are constantly framed in terms of God’s role in them, as though Beowulf owes all of his abilities to providence—an idea that hardly seems compatible with the earthly boasting and reputation-building with which he occupies himself throughout the poem. The conflict between the Anglo-Saxon idea of fate (wyrd) and the Christian God was probably a widespread moral tension in the poet’s time, and it animates Beowulf from beginning to end.