The passage from Grendel which best illustrates the theme "there is a monster in every person" is B. Staring at his grotesquely muscled shoulders — stooped, naked despite the cold, sleek as the belly of a shark. (155)
Grendel's relationship with the humans is characterized by the emotional response to the concept of community. Grendel is frustrated with the world he is living in, the animals that surround him are dumb and undignified. Further, that her mother is driven by the emotional instincts. Therefore, Grendel is trapped in his own world where he performs one-way communication by talking to the sky or air with no response.
The human who resembles Grendel in many ways, most painful refusal comes from them as they fret and disgust to share any meaningful conversation with Grendel. Yet Grendel, so close to humankind he is kept at a distance. Grendel's tragic status is underscored by the Shaper's Tale of Cain and Abel ( two sons of Adam and Eve). Therefore, Grendel is a monster whose inner self-resembles with that of humans and his physical appearance prevent him to enjoy the companionship and comfort of the civilization.