such ashame the halo 4 flood are not canon (i think)
because so far the antagonists in halo are just the warrior-class-prometheans and the guerrila covanent reminants
although the presence of the crytum [that giant sphere] makes me think the didact will return, i still have no idea which didact it is (there are 2 didacts according to the previews of halo: silentium; one is the original [which was executed by faber, the masterbuilder and leader of the ecumene], and the other is the bornsteller reincarnation)
Bornsteller is a forerunner teenager (nicknamed “manipilars” because of how they lack any genetic mutations/augmentations that adults would possess; essentially they are the “pure” forerunners)
Didact is the leader of the warrior-class-prometheans (the military basically) and is a promethean himself, and is also the husband of the librarian (a lifeworker who indexed the species of milky way before the halo activation)
Didact cloned his memory into Bornsteller so that he could essentially live on (because Faber intends to execute him); in which Bornsteller recieves his first mutations, and therfore is now a promethean himself
If the Didact entity will make a appearene in halo 4, it could be the Bornsteller-Didact
but Halo: silentium seems to imply that the original Didact DIDNT get executed, but rather traveled the universe to keep a “unimaginable evil” at bay (most likely the precursors)