Who was the Primarch of the Blood Ravens?

Question

I was playing Dawn of War 2 lately and I was wondering who the primarch of the blood ravens was?

Answer 1

It is unknown... but its highly hinted that it was Magnus the Red, primarch of the traitor legion Thousand Sons.

Its never officially stated, but there are few hints:

• The Thousand Sons Fellowship of Corvidae guided by Revuel Arvida didn't participate in the Fall of Prospero. Their motto was "knowledge is Power", their symbol was raven (corvidae is the name of bird family, that ravens belong to).
• Their have unusual high number of psykers, just like the Thousand Sons
• They share the TS obsession with secret knowledge and relics
• Their colours are suspiciously close to pre-heresy TS ones
• If you play as Imperial Guard and destory their base in the "Dark Crusade", the aftermatch information mentions that Blood Ravens bombarded their own positions just to destroy some data, yet enough left to bring them to full inquisitorial attention.
• In DoW II, entombed in Dreadnought armour Davian Thule (army leader in Dark Crusade) says that what he found during that campaign will be never spoken of.
• The psyker Kallista Eris had a vision concerning the fate of the Thousand Sons shortly before the Burning of Prospero. Among other things she mentioned "The Ravens. I see them too. The lost sons and a Raven of blood. They cry out for salvation and knowledge, but it is denied!"
• During an incident on the planet Arcadia, Librarian Rhamah of the Blood Ravens suffered amnesia and fell in with the Prodigal Sons warband of Thousand Sons sorcerer-lord Ahzek Ahriman. Throughout this association Ahriman and his warband referred to Rhamah variously as "Son of Ahriman", "friend of Ahriman" and as a "lost brother". Furthermore, when Rhamah locates an ancient Eldar tome - called the Un-Founding - that bears the crest of the Blood Ravens upon its cover, Ahriman concedes that he once owned a copy of the book and that another one was in the possession of Azariah Vidya (of whom Ahriman states, "I knew Vidya better than you might expect"). He further states to Rhamah "We are not so different, you and I. We were not always so different...there was a time, long ago, before the Change, when the Thousand Sons of Magnus wore the blood-red armour of their Primarch." No explanation is given for what any of this means, and it should be noted that Ahriman is a master of deceit and trickery who was attempting to use Rhamah for his own ends.

Other theories include that they origin from Dark Angels (they have similar love for secrecy), Blood Angels or Raven Guard (because of the name, but they don't share the genetic faults of those chapters), Imperial Fists (they had Rogal Dorn weapon... but Blood Ravens are known to be quite a kleptomaniacs) or simply Ultramarines, like about 60% other loyalist chapters.