"Celestia is what Platinum wanted. She knew the time was coming for the three tribes to unite, and since Faust was responsible for holding the Windigoes back, capturing Faust released them and triggered the exodus that led to that, which was a rather happy-ish accident. Platinum wanted Celestia to raise to become the ruler of the united tribes, which I know sounds altruistic, but isn't when you consider that Celestia was raised for that position by Platinum herself."