thousands/millions of years ago he was a major part of a war between the Forerunners and Humans. After the war, he exiled himself in a Cryptum, only to be awakened by a young Forerunner named Bornstellar Makes Eternal Lasting and his two human companions. Over the course of the novel, he eases up towards the humans and begins to respect them. By the end of the novel
Spoiler
he actually dies at the hands of another Forerunner, but is, in a sense, reborn in Bornstellar.