If you are talking about Beowulf, then Grendel is the representation of Cain. He is descendant of Cain, who committed the first murder ever. Cain and Abel were Adam and Eve's sons, and since Cain was jealous of Abel, he killed his own brother. Thus, every descendant of his is cursed, which is why Grendel is a monster.
Of the memory stages, it would be memory storage that has the greatest capacity and has the longest duration. The three memory stages are encoding, storage and retrieval. To gain new information, we first encode it to our brains, then store it and eventually use it or retrieve that information.
