Why is grendel a flat character in beowulf

Grendel is a flat character in Beowulf because he has a one-dimensional personality.

Explanation:

In the story Grendel stays a mystery as the story is told from the third person point of view. What makes him seem evil  is that he is a descended from Cain. There is less development in the character of Grendel and have been provided with an unclear descriptions.

Grendel is sometimes referred to as a flat character because he does not show a complex range of emotions, he is known as a monster, and doesn't change throughout the story, which makes him seen as a flat character.

caliban is prospero's slave in the shakespear's play "the tempest"