I think this is a question that hasn’t been discussed yet, but is it possible that the Bornstellar Didact could fight against the Ur-Didact in Silentium? I feel that it could happen, and I have a whole theory that goes with it.
I think that when it was discovered that the Ur-Didact was discovered alive and returned to Forerunner controlled space, the Bornstellar Didact was told that he no longer need to serve as a reincarnation of the Didact and would be mutated to a new form, which would not bear any of the Didact’s personality and memories, and would be sent back home. Bornstellar is against this plan, as he wants to continue helping the Librarian and the Didact, but the majority rules.
After this, Bornstellar is mad and feels hurt about the decision and decides to give up and not care anymore about the Didact, Librarian, the Precursors, and doesn’t want to be apart of the conflicts anymore because he was refused to continue helping.
This is where the Halo 4 terminals enter the theory. After the Ur-Didact composes the humans on the Halo ring, The First Councilor Splendid Dust of Ancient Suns, the Warrior-Servant Glory of a Far Dawn, and the Librarian’s Ancilla, (three characters from the first Forerunner novel, Cryptum) realize that Bornstellar needs to become the Didact again and help the Librarian stop the madness of the Ur-Didact. the three of them go to Bornstellar’s home and tell him of what had happened, and that he is needed again. Bornstellar refuses, saying that he was refused to continue helping the first time, which had hurt and angered him, and doesn’t want to go back to that life ever again.
Dust, Glory, and the ancilla, seeing that Bornstellar will not help them, prepare to leave as Bornstellar returns inside his home. But while he is inside, Bornstellar keeps on thinking about how humanity will be composed by the Ur-Didact and how it may not even be enough to stop the Flood. It is here that Bornstellar realizes that he was meant to become the Didact, and that if he doesn’t help stop the Ur-Didact’s madness, who will? So he races back to Dust, Glory, and the ancilla just before they leave telling them his change of heart and decides to go through with it, but first, he writes a letter to his father explaining his reason for going back.
Bornstellar is mutated again with the Didact’s personality and memories again, and is the Bornstellar Didact once more, and goes to Requiem with the Librarian to fight the Ur-Didact before he leaves for Erde-Tyrene (Earth).
This is where the Bornstellar Didact fights the Ur-Didact in an epic confrontation, but Bornstellar loses the fight, but gave enough time for the Librarian to board the Ur-Didact’s ship, the Mantle’s Approach, and defeats him there, as seen in the last of the Halo 4 terminals.
The Librarian retrieves Bornstellar, who was knocked out from the fight but is ok, and brings him to Installation 00 (the lesser Ark) to activate the Halo Array.
Like I said, this is just a theory, but it could be possible. Sorry if it was a little lengthy. But what do you think? Do you think the Bornstellar Didact will fight the Ur-Didact in Silentium?
BTW, the poll is open until Silentium’s release date, March 19, 2013, which is 83 days away as of December 26, 2012. 
UPDATE
Actually, while I was looking back at Cryptum, I discovered two things that I had forgotten:
- At the bottom of page 254, Bornstellar mentions how he never ended up seeing his family “alive and free” ever again before he leaves for the Capital.
2.On page 328, Glory tells Bornstellar that if the Didact is found, then Bornstellar will serve as his second-in-command.
This seems to show that a lot of my theory is incorrect, as the Bornstellar Didact would still be allowed to serve with the Ur-Didact, and not sent back to his home. I still think he may write that letter, and a fight between him and the Ur-Didact, with the Bornstellar Didact helping the Librarian stop the madness of the Ur-Didact, is still possible. I guess will find out on March 19, 2013. 