Chief has a greater purpose.

Video from gamespot

Alright so in this video he talks about chief being seeded by the forerunners and he also talks about chief having a bigger purpose.
Just wanted you guys to see this.

Nice.

We already knew he was destined for greatness–the Librarian saw to that personally for millennia.

I wonder what seed it is.

Is he the reincarnate of the iso-Didact?