So...seeing as 343i is adding some content like terminals to H2A...I have my fingers crossed that they might do a little bit with Mendicant Bias. He is theorized (confirmed?) as the voice in the Mausoleum and is definitely the entity fighting Cortana from stopping the Dreadnaught's launch (as confirmed in Contact Harvest). I would love to see a little bit more of his story teased here, especially if he's making a reappearance in H5.

As an aside, I seriously, need to find some time to do a good write-up on his character...