Perhaps 'they' have not decided on the truth yet, but whatever the full truth was 10 000 years ago the DAs are faithful now despite the whole 'original sin' package. I remember in RT days when the Dark Angels wore black armour that the only background fluff suggested they had argued during the heresy as to which side to take, they chose the Emperor but whether it was settled by a vote or actual combat between factions was unclear, they seemed 'dark' because you thought they might be tempted by chaos in the future, now we know much more.
I have always wondered if there is a list with all the fallen on that they cross names off when they are hunted down, because surely some of those fallen who were scattered through time and space must have been killed in unrelated wars or accidents or appeared so far back or forward in time or space that they will never be accounted for, unless they were all roughly sent the same way/time ahead but then what have the DAs been doing these last 10 000 years?
Its a good background but I think DA stuff dwells on it too much as it is only once in a blue moon that they engage in fighting the Fallen instead of the numerous other foes, and 85% of the chapter know nothing about it.
