If anyone is into the lore of Halo there is a pretty cool series on Soundcloud right now called Hunt The Truth. Up to Episode 10 now. Not sure how many there will be.
Its the ramblings of a journalist who was given the job of writing a puff piece on the chief by ONI. Of course when he starts to pull at threads, a dark sinister cover-up is laid out. Its starts off slow with a lot of the stuff already known but it sheds some like on the back story to Halo:5 and why they are calling the Chief a Traitor.