POSSIBLE SPOILERS
So I know that the campaign to Halo 4 has already been leaked but I don’t want to see it. Instead, I wanted to piece together the puzzle for myself. I THINK I may have put it all together. SPOILERS START HERE So we start with the fact that the Bornstellar-Didact is (as far as we know), the last remaining Forerunner in the galaxy. Before the activation of the Halo Array, he discovered a love for humanity. His closes companions – before the activation – were two humans. Why is it now that the Didact is killing humans in Halo 4? My idea is that after he fled to Requiem, he began to go a little crazy and lonely. Most likely, he would die for a chance to interact with another Forerunner. I think he got this chance when he discovered in the Forerunner Archives or “Bestiarum” that re creating Forerunners is possible. The Bestiarum reads that , “DNA/RNA/Silicon samples are encoded in this datastream. Reproduction of individuals for analysis is prohibited by this facility.” These samples have been theorized to be John’s or Halsey’s but I think they’re Forerunner. With Forerunner DNA manipulation tech, they could easily recreate new gene pools. I think the Didact wants to use Requiem as a breeding ground for a new Forerunner Empire. However, when humans and covenant alike arrive at Requiem, the Didact realizes he must kill them all or risk the exposure of his plans. “But then why would Prometheans be fighting WITH covenant?” The Didact knows humans can beat Covenant and probably the Prometheans as well but together? The Didact wanted to wipe out Humanity on Requiem, then turn on the weaker Covenant. This is why he lets them all enter, so he can kill them to prevent them from spreading word of Reqiuem. “Why would it matter if humanity finds out about Reqiuem?” Because if they find out Forerunners are coming back to reclaim their position as “Guardians of the mantle”, they could try to stop them. The Didact needs the element of surprise to take control again. So those are my thoughts on Halo 4! Please don’t post spoilers about the Campaign I don’t want to know. Also, don’t confirm or deny my theory, just ask questions or add your input. Let me know what you think!