- last post: 01.01.0001 12:00 AM PDT
I've got it!
How about, prior to the trailer, MC kills truth, thus bringing the Covenant force to disarry. Cortana gives away Earth's location to Grave mind, and he shows up in High Charity (which has become the Flood Hive). Arbiter shows up, and in the absence of a leader, the covenant follow him: the Brutes of course being beat into submission like -blam!-es.
Under the threat of the flood, the Humans and Covenant now form an alliance [*pukes on shoe*]. Now knowing the truth about the Arc from Guilty Spark, they have no choice but to find the Arc, and use it to destroy all life forms (thus destroying the flood) while they remained protected by the Arc.
So in the trailer we see the Master Chief and his new Covenant chums headng towards the new found Arc (hence they don't attack him). We can't see who's in the Banshee, because it's piloted by a Grunt.( Who would usually run from MC anyway). Of course once they reach the Arc, it unexpectedly opens up, bright light and all, because they just woke up the sleepy Forerunners.
Sure it's a crap theory, but it covers all the events of the trailer, so lets just accept it untill the game comes out and we know what's really going on OK?