Foil
Character Role Analysis
Beowulf
Here's a little piece of Old English trivia: in Beowulf, both the monster and the hero are described using the same word. The Anglo-Saxons had a pretty clear sense that there was a certain special something about both of these characters that kept them in the same category. Both of them were loners, both were huge and incomparably strong, and both had their own codes of ethics (often outside the norm).
This characteristic fascinated Gardner so much that he included it in his narrative. We're totally meant to look at these two characters and say, "Okay, which one of you is the monster?"
It's a tough call. Beowulf in Gardner's novel is a scary dude: it's like he has no soul. Maybe he's operated by remote control? And if so, who has the controls? Something ruthless and demonic, it seems. Grendel often gets the sense that Beowulf's lips don't synch up to the words coming out of his mouth, as if here were a character in a badly dubbed kung fu movie. And then Grendel sees Beowulf morph into something like an angel in their final battle.
So who's the monster? We can't tell you—but we can tell you that we would be really freakin' scared if we ran into Beowulf in a dark alley.