What is the basis of the conflict between Grendel and Heorot?
The word “conflict” is a little askew here, because Heorot is a meeting hall, not a combatant. But whether the anonymous author was working on this level of abstraction on not, modern interpretations take into account the conflict between natural order and man-made order—in other words, man’s intrusion on nature. If we see Heorot’s inhabitants as intruders on Grendel’s “environment”, we might take Grendel’s side: once free to roam the land in search of prey, Grendel is now restricted by human activity in the hunting ground around his and his mother’s home pool; his natural instincts are to combat those intruders. Think of a hunting lodge built in the middle of a forest; surely the grizzly bears would have the instinct (and the right) to attack the intruders. The Christian/pagan conflict (or, as Levi-Strauss would say, the raw and the cooked) is ubiquitous, in life and in literature, especially in early narratives of human expansion, conquest, and colonization.