Contrast the role of the lady in Lay of the Were-Wolf with a female character in Beowulf.

In Lay of the Were-Wolf, the lady plays two roles: that of supportive wife and villainess. In Beowulf, Grendel's mother also plays two roles. Besides being the chief villainess, she is also a grieving mother, a maternal figure who seeks revenge for her son's death.
The chief contrast between the two female characters lies in the difference between their individual villainess roles. Even though the lady in Lay of the Were-Wolf is the chief female villain in the story, she is never characterized as a monstrous anomaly. Grendel's mother, however, is characterized as a cursed descendant of Cain. She must live on the fringes of civilization, away from refined society. Additionally, she is portrayed as a hideous, masculine creature who delights in bloody rampages against noble knights.
Grendel's mother is so spectacularly degenerate and malevolent that Beowulf cannot destroy her with his sword, Hrunting. Instead, he must use a magical sword to kill her. 
In contrast, the lady in Lay of the Were-Wolf (although also a villainess) enjoys a high status due to her connection with the baron and then the knight. She doesn't betray Bisclavaret out of revenge but out of fear for her own safety. In contrast, Grendel's mother attacks King Hrothgar's knights to avenge the death of her son.
While Grendel's mother outwardly challenges the bravest knights in battle, the lady in Lay of the Were-Wolf is not confrontational at all. She may be a villain, but her villainy is practiced through equivocation and subtle acts of treachery. She doesn't reveal the extent of her betrayal until she is subjected to torture on the king's orders.
So, the contrast between the role of Grendel's mother and the lady in Lay of the Were-Wolf is evident: both are the chief antagonists of their respective stories, but both are portrayed differently in that role. While the lady of Lay of the Were-Wolf retains her privileged position in society, Grendel's mother is portrayed as a marginalized monster with unorthodox attributes.