I’d like to understand how the story from the Halo 3 Terminals fits into the Halo 4 story if it does at all. Cuz in the Halo 3 terminals, from what I’ve read, the Didact and Librarian are communicating with eachother in the final days before the array was fired. But in the Halo 4 terminals, the Librarian betrayed the Didact and put him to rest in Requiem before the array was ready to fire. So, I’m wondering is the Halo 3 terminal story obsolete? Or is there an explanation for how the Halo 3 terminal story fits in to the Halo 4 story?
To make a horribly complicated backstory a little bit more simple, there are two Didacts. Think about what the Librarian said to the Master Chief in Halo 4 - the very fact that he exists is an eventuality made certain by an “imprint” she created. It’s very much “space magic”. Well, the two Didacts situation is kind of similar. The Ur-Didact put an “imprint” of his own personality into a Forerunner named Bornstellar Makes Eternal Lasting while said Forerunner was undergoing a mutation. Eventually, that imprint took over Bornstellar’s mind, and he essentially became the Didact. The memories, physicality, and personality (for the most part) carried over.
I’m sure you can see the answer from here. The Librarian imprisoned one of the Didacts in a Cryptum on Requiem, while she and the other one went on the fire the Halo Array, as seen in the Halo 3 Terminals. It all fits together, it’s just really convoluted, likely due to 343 Industries wanting to have the Didact be a villain in Halo 4.
Which Didact plays which role is not fictionally certain yet, but things are popularly pointing to Ur-Didact being the one imprisoned on Requiem, while Bornstellar-Didact is the one who fired the Halo Array.
Go and pick up and read Halo: Cryptum and Halo: Primordium. They’re great novels that will give you good insight into the mutation process that essentially created a second Didact.