The Chief is not finding the ARC, even tho he dose, on earth, Every Pro halo fan knows that what the Profit of Truth wanted from earth was the ARC, and the arc is the big ass structure in the middle of Africa. Now, there is 6 Halo rings, if you look at it on the end of halo 2, 1 has been destroyed.

The Chief is only trying to save the humans from the covenant, But his True mission was, To lead and command his Spartans to capture a Covenant profit. But he got side tracked by the Attack on Reach, they fled to find halo, and learned it's real purpose. witch is to stop the floods food source and that is every living thing.

Some people like the fact of having 1 Spartan left, i wouldn't mind having them split up, like in halo 2 Arbiter and Chief.