This article contains spoilers for Halo episode 2.
Paramount+'s Silver Team in the show rather than Blue Team. Probably the biggest change to date is in of just who can use Forerunner technology.
Halo's central concept is that, millennia ago, a powerful race known as the Forerunners created the ancient Halo Rings to wipe out all life in the galaxy - a last-ditch attempt to destroy the food source of a parasitic infection known as the Flood. Humanity is a survivor of this ancient cataclysm, and the Forerunners programmed human genes with what they called a "geas," or "genesong," granting every human being the ability to use their technology. The alien Covenant may venerate the Forerunners, but only humans can use their artifacts.
But the Halo TV series seems to have switched this up. In Halo, not all humans possess the Forerunner genesong allowing them to become what the Covenant and their Prophets call "Reclaimers." Rather, the Covenant has learned only a minority of humans can activate Forerunner technology; to date only two have been identified, the Covenant's Blessed One Makee and the Master Chief himself. It's unclear whether the Forerunner genesong has been diluted in most humans, or whether there's something unique tying these two characters together. In an interview with Decider, showrunner Steven Kane refused to answer whether the two are linked to one another.
In narrative , this approach makes perfect sense. It means the Master Chief and Makee are essentially the two most important people in the Halo TV series, simply because they can use Forerunner technology - up to and including the Halo Rings, which could wipe out all life in the galaxy. The interesting question is whether or not there are others who possess the Forerunner genesong; specifically, it's quite possible all other Spartans do. Dr. Halsey used genetic screening to choose her Spartan recruits, and the parameters of this screening could have unwittingly been looking for evidence of Forerunner genes.
The Master Chief has only just begun to learn the truth about the Forerunners - and, as a result, he's only beginning to understand the Covenant's true motives. No doubt this theme will be further explored over the course of Halo season 1, as Dr. Halsey attempts to understand the mysterious Forerunner artifact the Master Chief has retrieved from Madrigal. And it will all inevitably lead to the Halo Rings themselves, where the fate of the galaxy will be decided.