No...it is not a proper noun.
The correct answer is sympathetic.
If you read Beowulf, you will see that Grendel is a vicious monster who doesn't care about humanity at all - people are there just for him to eat. On the other hand, if you read Grendel, you will see what happened from his point of view - that he is not just a brainless beast, and that he has thoughts and feelings.