I just finished book 2, so I am not ready for any spoilers yet, but the whole entire trilogy seems to be based on a recording found from Chaplain Boreas.
I honestly don't remember who that is, but, and without giving much away, the recording sounds vaguely similar to a Dark Angels short story I read YEARS ago, about a 5-man squad with their own keep on a recruiting planet, and the squad gets infected with something diabolical virus. With the decision falling to their Chaplain (don't remember who) they opt to spare the planet from the disease and atmospherically seal themsleves inside their keep, never to be seen again..... <-- anyone remember this story? And if so, is this new trilogy based on the short story?