Answer:
A terrible monster haunts the halls of Herot. Beowulf has to fight this evil fiend. No doubt, the reader sympathizes with Beowulf for he will have to fight this monster. After hearing the details of Grendel's awful attacks, anyone would be afraid to encounter Grendel:
[Grendel] arrived when the soldiers were sleeping and attacked, killing 30 of them. There were tears and laments, but he attacked the next night as well.