Forerunner
Why?
That was what Faber thought as he overlooked what seemed like Erde-Tyrene from orbit. The reason for this confusion was that he knew for a fact that this was not where Erde-Tyrene was in space. Therefore, this is a replication of the planet. The question here however, is why did someone create a replica of the human homeworld?
He had a theory of course, the old stories that the builders held dear implied much. Among those, were tales that the Precursers never intended to give the Mantle to Forerunners, that they would have the Humans assume it instead. A horrible, but entirely possible senario, given what the Librarian had discovered in Path Kethona.
But he did not want to ponder why the Precursers chose to give the mantle to the vastly inferior Humans. He did not want to consider what flaw the Forerunners had, to cause them to be so overlooked.
Instead, he wanted to know why creating a second Erde-Tyrene was necessary in this goal, because surely no Forerunners could have done this - he would have known.
However, Faber knew that uncovering this worlds secrets would take time. He would need a way to secure - and hide - this planet, to give him time to study it. Eventually, an idea occured to him.
"Silence!" He called to his aid, Silence-of-far-suns.
"Yes Master Builder?" He responded as he walked towards Faber.
"Has the Didact designed any of his shield worlds that are of a sufficient size to contain this system?" Faber believed he knew the answer, but wanted to be sure.
"Yes Master Builder, the Didact has a shield world big enough, 006, which could fit the system." Silence responded, likely being informed by his ancilla.
"Inform Former-of-Ancient-Worlds that I want a shield world of similar design to 006 constructed around this system, and to meet with me to discuss this matter further." He ordered, already forming a plan.
"Of course, Master Builder." Silence said as he walked out of the viewing area.
Faber pondered his decision as Silence left the room. Ancient Worlds had definitely proven his capabilities while assisting him with the creation of the greater ark, and would do well on this task. Faber did not wish to oversee the study of this system himself, as he would rather not deal with humans any more than he had to.
Either way, he had more important things to attend to, like the oversight of these new Halos. They would, after all, be the Forerunners last hope against the coming Flood.
----__++==++__----
The Librarian planned for this.
She did not know for sure that this would happen, but it was clear the Precursers had made a plan. Instead of simply being defeated, they ensured that eventually, Humanity would have the mantle.
And now the time has come to pass it on.
The Forerunners time of control over the mantle of responsibility has ended. Halo will fire, the Flood will be eradicated - if temporarily, and the mantle, protection of the galaxy, would be passed on to its rightful owners - she had made sure of this.
But the plan the Precursers made to ensure this was clearly very complicated. The evidence of which was seen in the secret shield world.
The Master Builder found a replica of what would be called the sol system. In his goal of learning what its purpose was, he put it inside a shield world, hid it from the council, and never gave a thought to it again.
Now, perhaps only weeks before her Didact activates Halo, she learns of this world, with its own population of humans. The difference that seperates this planet from the original Erde-Tyrene? An undescribable force resting both within the planets and some of their inhabitants.
And to ensure that this force survives, she needs to ensure that Halo does not touch this world.
A tall order, but not impossible. No, the part that will be the most challenging is laying her geas in the humans, before the Ur-Didact makes his move - and she knows he will.
If he succeeds, at least she will know that another group of humans, with this force to assist them, will be able to take their place instead. And if he fails, if her humans survive to be reseeded, well she has made plans for that as well.
But she must get started, after all her existence in living time is short, and the Forerunners final great journey is at hand. The mantle of responsibility will soon belong to the reclaimers, and if all goes to plan, they will meet magic as well in their ascent to the stars.