In Beowulf, there is a contrast between Herot and Grendel's home.
Herot is equated with God and heaven. It is associated with companionship and good deeds. Herot, then, represents goodness and honor.
Grendel, however, is connected to the devil and his home is associated with hell. He lives isolated and alone. He is said to be a descendent of Cain, meaning that his being is full of sin and evil.
These descriptions set up a conflict of good versus evil.