Okay after searching the googles for a while, I came across this http://www.forwarduntodawn.com/the-master-builder/
and started looking, I am always thinking about the master builder but hardly ever had enough to back it up, well this is my chance
since we all know master builder built the halo rings and knows how to use them and his motive, lets just say hes really pissed off
since there is 2 more halos to be heard of, maybe we might have 2 main enemies? and kill them both in halo 6?
since the Flood won't be our enemy in Halo 4 maybe Halo 5 or 6? I have found this line of text on the infamous timeless one.
the Timeless One said that it was the last “of this kind” [Primordium, C29P365] and that the Flood would continue its legacy–one which might be physically represented in the Flood’s form.
so the timeless could be considered another gravemind, and could be another enemy...
okay now for TheDidact since everyone is thinking it is him and it probally will be him
First and foremost, Didact has a rather significant history involving not only opposition to–but complete and open warfare against–humanity. During the Forerunner-Human Wars, when humanity was vying for new territory as the Flood claimed more and more of their worlds, the Didact led many campaigns against the humans, coming to know them as his enemy. Indeed, this deep seated hatred for the kind that killed many of the soldiers under his command was present even thousands of years after that war had ended, leading to an acute discomfort with having to even share the same vessel with the humans under Bornstellar’s charge. Would it be so hard to imagine a cause arising that allowed this hatred to reemerge?
[background=rgb(6, 6, ]but I just came across this which will help you guys prove it is TheDidact, since we all know we are fighting prometheans[/background]
Means - If any Prometheans exist, they would still be under the Didact’s command.
Motive - He never much liked humans anyway, and probably wouldn’t need much convincing to oppose them again.
Well thats all the info I can tie up here so I'll show you all three links below.
http://www.forwarduntodawn.com/the-master-builder/
http://www.forwarduntodawn.com/didact/
http://www.forwarduntodawn.com/the-timeless-one/