Each Forerunner goes through mutations to become mature some go through many more than just one. Bornstellar the Forerunner that the other user talked about was an adolescent (manipular). Bornstellar was imprinted by the Didact, at this time he became the Iso-Didact and the original was known as the Ur-Didact, it's confusing as the Iso-Didact then knows everything the Ur-Didact did [b]up[/b] to the imprint. If you think Ur = original and Iso = copy. [spoiler]Only one Didact remains.[/spoiler]