My personal head canon is that this was their original goal. But after that many years, I'm sure the warp has corrupted them... to a point, or some. And as much as I'd like to vouch for my personal favorite, Curze... I'm going to give the spotlight award to either Perturabo or Vulkan. Perturabo because I feel sad for him. Vulkan because he was all 'respect civvies, my sons' And they do, while most chapters are indifferent or outright hostile towards humanity as a whole - even if they fight for it.
I know they did one on one but the other two didn't, if Russ did indeed kill them ('cause a normal Space Wolf wouldn't kill a primarch) then that's pretty damn badass, although he may or may not have killed them but if he did he'd obviously need his legion because the other primarchs' would have at least some of their legions still loyal if they were traitors.
i think the Blood Ravens may have come from the Thousand Sons legion, due to the high amount of psykers
They've done a fair amount to throw bones to Relic fans, i.e. the seer at the end of A Thousand Sons, then the appearance of Revuel Arvida in Rebirth and Scars, but yeah, it's not set in stone (at least, won't be until the HH series is done and we hear what happens to Arvida).
Shame that. I enjoyed playing as the Ravens in DoW & DoW2. The mysteriousness of them kind of makes me more attracted to them if you get what I mean. I just wish someone would have the guts to expand upon the story with a couple of side stories just as filler before Relic bring us DoW3.
