After Beowulf severs Grendel's arm during the fight at Heorot, Grendel, knowing that his wound is mortal, escapes to his home in the fens.
Even though Beowulf's defeat of Grendel becomes the occasion of great celebration among the Geats and Danes, who believe the threat to Hrothgar's people has ended with Grendel's death, a more serious threat looms in the form of Grendel's mother.
After Heorot is restored to its original grandeur (before Grendel's attacks began), Hrothgar's and Beowulf's men celebrate Beowulf's triumph over Grendel and sleep in the hall, completely unaware that trouble, in the form of Grendel's mother, is on its way!
Beowulf's defeat of Grendel is actually just a prelude to the battle with Grendel's mother, who is animated by not only her hatred of men but also her desire for revenge and is much more powerful and dangerous than Grendel.
The question I pose to you is this: Is Grendel's mom really a villain or just a grieving mother?
What does Grendel's mother have for breakfast? Coffee and a couple danish.