Imagine two siblings, a little boy and a young girl, playing together on the soft carpeted floor of a typical family living room. The girl accidentally knocks over the tower the boy was making with Legos, thus angering the boy and giving him an incentive for revenge on the girl. He hits her, starting a cycle of vengeance. The girl, who is now angered at her brother, tells her mom and gets the boys Legos taken away. She feels satisfied because she has been granted her revenge. The boy now has no toys and is sitting in the living room watching his sister play with her Barbie, naturally he will want his revenge and try to get her toy taken away. Revenge and vengeance are prominent themes in Beowulf. While the example above is merely represented with children, you can only imagine what severe depths it can reach in larger proportions. "Revenge proves its own executioner" (John Ford, The Broken Heart).
The first representation of the theme of revenge in Beowulf, is shown in the relationship between Grendel and the Danes. The continuous cycle of revenge is begun by the evil beast Grendel. Grendel descends from the biblical Cain, who committed the first murder by killing his brother out of vengeance for not being the favored one by God. Grendel holds great despite for the Mead Hall the Danes have built in which ceremonies and parties take place long into the night. He takes his revenge by terrorizing them and their town, occasionally eating some of the Danes. Beowulf comes to the Danes in search of a way to greaten his legacy through battle, thus the Danes send him to gain their revenge on the monster Grendel. Beowulf and Grendel have a toe-to-toe brawl in the Mead Hall, ending with Beowulf ripping off Grendel's arm, forcing Grendel to flee and await his sluggishly approaching death.
The theme of vengeance once again crawls back onto the books pages when Grendel's mother hears word of her son's death and wishes revenge against the Danes.