Disclaimer: i have not read the books, so excuse me if there's a hole or two (dont flame, explain :) ). But i do know some things because of Halopedia, lol.
anyways, there is talk in other forums that these spartan's may be part of a class 2 division because of their service tags. Is is not possible that these 2 class spartans, plus a possible woken up master cheif, could be trying to take back reach as a colony, now that the covenant have been defeated?
this is just a possible thought, but seeing as how the tag is "Falls 2010" we're supposed to infer it is about the "fall" of "reach" but we'll see i guess.