Three reason why Grendel from Beowulf might have led a painful life?

One reason Grendel led a painful life is that he was a descendant of Cain. From the beginning he was born out of pure evil. Another reason Grendel may have led a painful life because he was compared to a beast. The motives of this beast was to stop any festivities in Heorot Hall; which caused him to be a primary target of King Hrothgar. A third reason is the fact that Beowulf came to kill him. Clearly fighting the protagonist is a painful endeavor. Also Grendel is impatient with the music and celebration of Hrothgar's men; his home is a hell on earth; he was born in slime; his parents are the children of Cain, who were exiled by God; he is family to "a thousand forms of evil," who angrily fight against God.