Apologies if this has been discussed already. If so, please link me to the relevant thread(s). The search function doesn’t seem to work (I highly doubt that there are absolutely no posts containing “faber”).
Anyways, if this hasn’t been discussed, then I would be quite surprised. Faber seems almost like an obvious choice as the Ancient Evil, and the precense of a Cryptum and hostile Forerunner technology/beings (which is pretty inconsistent with post-array-firing Human-Forerunner encounters elsewhere) on Requiem seem to really fit.
In Primordium and and Cryptum, Faber seems like a huge jerk who is concerned about his own power and his own policies above all else.
That the Didact or some remnant of him appears on Requiem (and in the game, Halo 4), actually makes even more sense with the idea as Faber as the enemy because it would give the players who know nothing of the extended fiction a guide and explainer as to the conflict between Faber and other Forerunners (and the Didact too).
This I think would go a long way to explaining the presence of immediately hostile Forerunners and would make a lot more sense than Didact vs Humans.
The ancient conflict between humans and Forerunners was a political one, a conflict that manifested in war, yes, but the punishment of humans by Forerunners seems to be more out of mistrust, fear, and the greater “good” rather than hate (they could have wiped them all out if they wanted too). With this understanding, it wouldn’t make much sense for the Didact or whatever the Didact-thing is to be so hostile (and call him evil) given the depiction of the Didact’s behavior so far. The Didact is angry with humans over the war, but he does not hate them and does not appear to be evil.
Faber, however, fits the bill perfectly IMO, and I could even imagine him allying with the Primordial and or Precursor remnants, if he felt it was to his own selfish benefit, even at the cost of others.
I loved it