One primary feature of grendel's home is that it is

The feature of grendel’s home is considered to be a subterranean in which is located under the surface of the earth in which Grendel made because of his way of protecting himself from humans who he had made conflict with.

One primary feature of grendel's home is that it's subterranean (located underneath the surface of the ground). Due to the conflict with the humans, it is important for Grendel's home to be lcoated in a place that couldn; t be reach by human so it could serve as a protection/hiding place from any potential attack by the humans.