I've just finished this book and I'm dying to know one thing: who the hell is Epimethius?
This Grey Knight, who's one of the main characters in the novel, is referred to as one of the founding members of the order who fought in the Horus Heresy (he's found in some kind of stasis-state) and that "Epimethius" is simply a cover name for someone else, someone to whom Supreme Grand Master Kaldor Draigo refers to as "Lord" in an awed whisper. Abaddon said:
Abaddon also said he was interested in Epimethius's gene seed, which earlier in the book was revealed to have come from the Emperor. I got the impression that this isn't typical of all Grey Knight's, further implying something very special about this particular Grey Knight. Abaddon ruled out the possibility that Epimethius was really Loken because he said he "watched my erstwhile brother die". He then asks the Grey Knight if he's "the Ultramarine" before ruling that out because he didn't "have that look about him".
I got the impression that Epimethius was a Dark Angel or maybe a Night Lord, but whoever he is he's one of the ten founding members, apparently. Does anyone know?