Ok since Zita doesn't know: Chief has a geas of the IsoDidact, right?
I don't think it has been officially confirmed in the lore but its been implied or at least its a very possible theory that would explain some stuff
I think this all originated from when Bornstellar asked Monitor Chakas if it was his choice would he activate the rings (in Silentium).
Then in Halo CE, Guilty Spark said "why would you hesitate to do what you have already done?" (Which we know bornstellar was the one who activated the rings)
And Spark also said to Chief "last time you asked me if it were my choice would I do it? Having had considerable time to ponder your query my answer has not changed. There is no choice, we must activate the rings"
I think there's possibly other stuff in halo 4 and possibly some comics I just don't remember
