From the SDCC 2015 ‘Hunt the Truth: Following the Trail of the Halo 5: Guardians Story’ panel. [x]
“Osiris is having to pursue Chief, and they’re having to seek out people who can give them insight into Chief - and, obviously, Arbiter is one of the few people out there who knows Chief better than maybe he knows himself.
So we find ourselves on Sanghelios, Arbiter however is also very busy with the civil war - the Covenant has fallen apart, the Sangheili are trying to figure out what that means for them. So we’re thrust into the middle of that civil war and Arbiter is trying to do his best to help us, but we also have to help him.”
“And it’s obviously the first time in the game that we get to explore the Elite homeworld, and this is one of those things we talked about many games ago […] the Elite homeworld is, at various stages in the Halo history, the absolute nexus of the Covenant’s military might - moreso than the Prophets even, for obvious reasons. So it’s going to be fun to go and explore all that culture and see the kind of world that built that kind of antagonist, and there’s a lot of storytelling even in the environments in that regard.”