In this section, Grendel is made to seem totally evil, with no redeeming qualities. The narrator tells us that he "relished his savage war on the Danes"
and sought no peace, killing indiscriminately and at will. Do you think that a
character this unilaterally evil is an effective antagonist? What would happen
if Grendel had a "backstory" that gave him a legitimate motive for his
behaviors? What if he had some sympathetic or redeeming qualities

which is the following what are you asking?

throughout the ancient epic of gilgamesh, the protagonist, gilgamesh of course, exhibited many character traits that made him a true epic hero. one great trait that gilgamesh acquires of an epic hero is that he's a courageous and confident leader. in the text enkidu is too afraid to fight, but he's positive that gilgamesh has the ability to triumph against humbaba. gilgamesh tells enkidu to not be afraid and then continues on to remind him of all the victories he's had against similar foe. gilgamesh proves that he's confident by encouraging enkidu and shows he's courageous when enkidu ask gilgamesh to battle humbaba alone because he knows that gilgamesh will reign victorious.

another characteristic that makes gilgamesh an epic hero is that he's brave and takes risks. "dread surged through gilgamesh, terror flooded his muscles, his heart froze, his mouth went dry, his legs shook, his feet were rooted to the ground. / gilgamesh felt his courage return. they charged at humbaba like two wild bulls." when reading the first part of the quote you see that gilgamesh is terrified of humbaba, and realizing that humbaba is the antagonist he's about to battle is taking a big risk. gilgamesh soon shows how brave he is by not letting his fear of humbaba overtake him, instead he went charging into the face of fear and triumphs.