As most adults know, there are no such things as monsters. Ever since childhood, almost every child, at one point or another, has been told by their parents that monsters do not exist and that there is no reason to be frightened by these imaginary creatures. Similar to the things that parents say to children about those monsters hiding underneath their bed, the monsters of Beowulf, translated by Seamus Heaney, are not real, but fictitious creatures representing evil because of their attacks on the Anglo-Saxon societies. Grendel, his mother, and the dragon are the imaginary creatures that originate from Cain, which causes Beowulf, the Geat hero, to come to the rescue.
Cain is the source of all evil and monsters. Ever since he was born, he was insincere and selfish. The ultimate sin that he committed, which also defies the Anglo-Saxon value of brotherhood, is killing his blood brother, Abel, when Abel's offering was accepted and his was not. Greed, jealousy, selfishness, rejection, and discontentment drove Cain to kill his brother. "For the killing of Abel the Eternal Lord had exacted a price the Almighty made him anathema and out of the curse of his exile there sprang ogres and elves and evil phantoms and the giants too who strove with God"(lines 107-113). All the monsters, including Grendel, his mother, and the dragon, were spawned from this one person who represents all evil, which makes them evil too. The country peoples describe Grendel and his mother as "fatherless creatures [whose] whole ancestry is hidden in a past of demons and ghosts"(lines 1355-7). These "fatherless creatures" are homeless and wander aimlessly around. Due to the fact that they are from an evil family, they don't really have a home of warmth and love, which contributes to their evilness. His past shapes their future. They all also defy the Anglo-Saxon values, which encompasses comitatus (brotherhood), loyalty, honor, duty, generosity, fame, strength, and unity.