As the warriors sleep in the mead-hall, Grendel’s mother, a horrible monster in her own right, descends on Heorot in a frenzy of grief and rage, seeking vengeance for her son’s death. When she falls upon and seizes a sleeping man, the noise wakes the others. The warriors seize their swords and rush toward her. The monster panics and flees, still carrying her victim, Hrothgar’s trusted adviser, Aeschere, in her grasp. Beowulf, having been given other sleeping quarters, is away from Heorot when Grendel’s mother makes her raid. By the time he arrives at the hall, she is gone. The warriors discover that she has stolen Grendel’s arm as well.

Devastated with grief over the loss of his friend and counselor, Hrothgar summons Beowulf and explains what has occurred. He entreats Beowulf to seek out and kill Grendel’s mother, describing the horrible, swampy wood where she keeps her lair. The place has a magical quality. The water burns and the bottom of the mere, or lake, has never been reached. Even the animals seem to be afraid of the water there.

Hrothgar tells Beowulf that he must depend on him a second time to rid Heorot of a demon. He says that he will give him chests of gold if he rises to the challenge. Beowulf agrees to the fight, reassuring Hrothgar that Grendel’s mother won’t get away. The warriors mount up and ride into the fens, following the tracks of their enemy. When they reach a cliff’s edge, they discover Aeschere’s head lying on the ground. The scene below is horrifying: in the murky water, serpents and sea-dragons writhe and roil. Beowulf slays one beast with an arrow.

Beowulf, “indifferent to death,” prepares himself for combat by donning his armor and girding himself with weapons (1442). Unferth loans him the great and seasoned sword Hrunting, which has never failed in any battle. Beowulf speaks, asking Hrothgar to take care of the Geats and return his property to Hygelac if he, Beowulf, should be killed. He also bequeaths his own sword to Unferth.

The intensity of the epic increases in these lines, as its second part begins with the arrival of Grendel’s mother at the hall. The idea of the blood feud, which has been brought up earlier in the scop’s stories and in Hrothgar’s memory of the Wulfings’ grudge against Ecgtheow, now enters the main plot. Just as Grendel’s slaughter of Hrothgar’s men requires avenging, so does Beowulf’s slaying of Grendel. As Beowulf tells Hrothgar, in a speech with central importance to his conception of the heroic code of honor, “It is always better / to avenge dear ones than to indulge in mourning / . . . / When a warrior is gone, [glory] will be his best and only bulwark” (1384–1389). In this speech, Beowulf explicitly characterizes revenge as a means to fame and glory, which make reputation immortal. As this speech demonstrates, an awareness of death pervades Beowulf. That some aspect or memory of a person remains is therefore of great importance to the warriors. The world of the poem is harsh, dangerous, and unforgiving, and innumerable threats—foreign enemies, monsters, and natural perils—loom over every life.

One of the most interesting aspects of Grendel’s mother’s adherence to the same vengeance-demanding code as the warriors is that she is depicted as not wholly alien. Her behavior is not only comprehensible but also justified. In other ways, however, Grendel and his mother are indeed portrayed as creatures from another world. One aspect of their difference from the humans portrayed in the poem is that Grendel’s strong parent figure is his mother rather than his father—his family structure that is out of keeping with the vigorously patriarchal society of the Danes and the Geats. As Hrothgar explains it, “They are fatherless creatures, / and their whole ancestry is hidden” (1355–1356). The idea of a hidden ancestry is obviously suspect and sinister in this society that places such a high priority—a sacredness, even—on publicizing and committing to memory one’s lineage.

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.