After his meeting with the dragon, Grendel felt an air of futility and doom around himself. Also, the dragon had put a charm on him so that no weapon could cut him. This newfound invulnerability drove him to visit Hart more often, but also isolated him further as the humans could no longer really fight with him.
Grendel’s invulnerability isolates him further from the humans. While they had a chance to kill him, he felt some connection—they were equals, defining each other. Now that he is too powerful for them, that mutual definition is no longer operable.
In the summer of the first year of Grendel’s war with Hrothgar, Grendel was drawn to the meadhall though he had not yet begun systematic raids. He would wait at the edge of the forest, listening to the Shaper’s songs, which enraged him with their confidence and hope. He went up to the wall of the meadhall and peered in through a crack. The Shaper sang of how God had been kind to Hrothgar’s people, who were the richest and most powerful on earth.
The Shaper’s songs continue to irritate Grendel. However, his anger at their arrogance and ignorance is at least partially also jealousy of the humans’ community and their sense of hope. Grendel, with no community, has no hope. And he has no illusions about any gods giving kindness or blessings.
One night as he was doing this, a stick snapped behind Grendel and a dog barked. A guard discovered him and struck him with a sword, but could not hurt Grendel. More men came and attacked in vain. Grendel laughed. He had meant them no harm. He walked off, carrying the guard with him, and ate the guard. He returned to the woods happily.
Terrifying the humans brings at least some joy and purpose to Grendel’s life. Perhaps he needs them as much as they need him. Notice, still, how Grendel at this point kills only to eat.
Three or four nights later, Grendel performed his first raid. He burst into the hall while the men were sleeping and ate seven of them, taking joy in the killing. He says that he himself became the mother he had once searched for. He felt as though he had finally “become something” and called himself “Grendel, Ruiner of Meadhalls, Wrecker of Kings.” But, Grendel notes, he also felt more alone than ever.
Again, killing the humans makes Grendel happy and gives him an identity. He no longer feels the need to search for a companion in his mother. He has "birthed" himself as a "Ruiner of Meadhalls." Nonetheless, despite his antagonistic relationship with the humans, ultimately he still feels lonely.
A few nights later, Grendel raided Hart again. The humans tried to attack him bravely, but their weapons were useless against the dragon’s charm. Grendel laughed as man after man attacked him, shouting about honor, Hrothgar, and God. Though laughing, Grendel felt empty and imagined himself going on killing without difficulty indefinitely. Filled with rage, he smashed and destroyed benches, tables, and beds.
Grendel in his strength, and knowing the truth of the human's past, knows that the ideals of honor, king, and god are in fact meaningless lies. Yet the ease with which Grendel defeats the humans takes some of the joy out of his raids. He craves some kind of rival or struggle, some connection through mutual risk.
Then, a man named Unferth appeared. Grendel calls Unferth his salvation. Taller than the other men, Unferth took on Grendel single-handedly and acted like a righteous hero, threatening Grendel. Grendel laughed at Unferth’s heroic posturing and spoke back to him. Unferth was shocked to learn that Grendel could speak and pledged to kill him. Grendel responded sarcastically, mocking Unferth’s heroism and saying that he thought heroes only existed in poetry. Frustrated, Unferth charged at Grendel, but Grendel picked up apples from a nearby table and threw them at Unferth, hitting him so that he bled. Unferth slipped on the bloody floor, making Grendel laugh. Unferth attempted to charge again, but Grendel tipped the table of apples over on top of him. Unferth was extremely angered, but Grendel simply left. He says that he got more pleasure from that fight than any other.
Unferth attempts to provide Grendel with a rival, but he is not strong enough to be a true rival to Grendel. It is easy, therefore, for Grendel to mock Unferth’s ideas of heroism. Rather than fighting him, which would allow Unferth to be a kind of hero, Grendel humiliates him and makes him look ridiculous by pelting him with apples. Unferth’s identity as a hero depends on a cooperating monster. By refusing to cooperate, by fighting with apples rather than claws or swords, Grendel takes pleasure in destroying Unferth’s and the other humans ideals of heroism.
Grendel returned to his cave. Three nights later, Unferth arrived, having followed him. Grendel woke up startled, stopped his mother from going to Unferth, and went to see Unferth himself. Unferth was exhausted and injured by the firesnakes he had to swim by to get to Grendel’s den. He announced his arrival and said that his heroic acts would be sung in future songs. He waited for Grendel to kill him, but Grendel just watched him silently.
Unferth is desperate to be a hero, even if that means dying. By not killing him and not allowing him a heroic end, Grendel tortures him further.
Frustrated, Unferth told Grendel that he was wrong about heroism, that it really did exist and that Unferth was a true hero, because no one would know whether he found Grendel and died heroically or simply fled. According to Unferth, this defines “inner heroism.” Unferth continued to refer to himself as a hero, which annoyed Grendel. Grendel decided to carry Unferth back to Hrothgar’s meadhall safe and unharmed.
Unferth persists in his beliefs about heroism. In his mind, he is a true hero since he pursued Grendel to his lair even though no men will know of his deed. Grendel again frustrates Unferth’s attempt to be a hero by deciding to return him safely to Hart.
Unferth fell asleep and Grendel carried him back home, leaving him at the meadhall door. Grendel says that Unferth still lives, challenging Grendel in vain, ashamed that he alone is spared in Grendel’s raids.
By refusing to fight Unferth, by ensuring Unferth's safety, Grendel successfully demoralizes Unferth, making him lose faith in the idea of heroism.