The battle with Grendel finishes when Beowulf tears off his arm, and the monster runs away to die in the swamps. But Grendel’s mother was driven by vengeance. By night, she penetrated Heorot. She took away Hrothgar’s best advisor and Grendel’s hand. Later Beowulf found the advisor’s head near the monster’s lair.
Beowulf wanted to be loyal to Hrothgar, the king of the Danes, who saved his father long ago. That is why he intended to eliminate Grendel, the man-eating monster, who killed many Danes. The hero crossed the sea with fifteen warriors to fight the beast.
Beowulf fought barehanded and without any armor. He caught Grendel by his hand, and they wrestled all around the mead-hall. When the monster realized his helplessness, he tried to escape. But Beowulf ripped his hand off, and Grendel ran away bleeding. It was clear that the beast was going to die. The next night, Grendel’s mother came seeking vengeance. She did not do much harm but took Aeschere, Hrothgar’s favorite thane. The king asked Beowulf to avenge Aeschere’s death, and so he did. He entered Grendel’s mother’s lair and killed her in a fierce battle.
The outcome of the battle with Grendel extends beyond this monster’s death. It entailed his mother’s rage and vengeance. Her actions were justified because, in Anglo-Saxon culture, a surviving family member had to punish the murderers of the dead one. Meanwhile, Beowulf had to fight her to remain loyal to King Hrothgar. As one can see, no event in the poem is occasional, and everything has its cause and result.