What imagery associated with Grendel hints at his nature?

In the text, Grendel's movements are described as plodding and stalking, his claws are described as vicious and plundering, and Grendel himself is described as a demon. Grendel hated. He relished murdering his victims.

"Till the monster stirred, that demon, that fiend. Grendel who haunted the moors, the wild. Marshes, and made his home in a hell. Not hell but hell on earth. He was spawned in that slime. Of Cain, murderous creatures banished. By God, punished forever for the crime of Abel's death."

Grendel's hatred began, . . . the monster relished his savage war on the Danes, keeping the bloody feud alive, seeking no peace offering, no truce, accepting no settlement, no price in gold or land, and paying the living for one crime only with another. No one waited for reparation from his plundering claws: That shadow of death hunted in the darkness, stalked Hrothgar's warriors."