By the power of truth, I, while living, have conquered the universe.
So yesterday we caught our first sneak-peek at the incredibly sexy-looking Halo 4 and straight away when we saw this mysterious sphere we were thrown back into this ominous technological world of mystery.
In my opinion, the sphere is some kind of vehicle captained by a Forerunner inside - which could be supported by this image from Halo 3's Terminals. Back in the day, people speculated that this represented some kind of advanced combat skin used by the Forerunners as a defense mechanism. This may well be true, but I think that this could be quite similar in fuction to the sphere we see.
Them, when they first see the sphere appear, Cortana says "we know where he's heading" and John replies, "same place we are". So let's break this down.
1) Judging by the lack of surprise Cortana and John show, it's implied that they've already encountered "him" before that sequence of events.
2) The use of the word "him" imples some kind of identity associated with the sphere itself, reinforcing the idea that it's some kind of vehicle operated by someone.
3) This would now be at least twice that John has encountered and not been killed by "him".
4) The sphere scanned John and decided to leave him alone, implying it's friendly. It should also be noted that as soon as John sees the sphere and recognises it, he lowers his gun and just stares at it. Now if this was something new and that big, his most likely reaction would have been to either run like hell or start shooting at it, since he doesn't do this we can assert that the sphere is relatively apathetic towards his presence.
So who is piloting this sphere then? IMO, it could be the Didact - this brings me to my next point, the role he'll play in the game (if he is indeed present on Requiem).
I don't think that the Didact will be a villain, in fact I think that there's going to be several Forerunner factions. In this screenshot you can see what clearly looks like a shot discharged from the new Light Rifle heading in the direction of these almost friendly-looking Forerunners, now this may just be the player with a Light Rifle but I'm holding out on the possibility of there being several factions.
The line, "I have long dreamt of this day, Reclaimer" doesn't really carry any aggressive connotations to it in the way it's spoken, at least IMO. It sounds almost like relief being expressed to me.
And so, this would all slot together nicely if it is indeed the Didact piloting the sphere and not showing aggression towards John.
[Edited on 06.05.2012 10:25 AM PDT]