Blood Ravens having Red Thirst?
In DoW2, the "chapter's Fury" perk of Thaddeus sounds very similar to that of the red thirst, not exactly the same, but very similar. Along with this, they're called the Blood Ravens, while obviously the two share the blood in the name, Sanguinius referred to as having raven like wings in Sanguinius: The Great Angel. IF this wasnt enough, there's still the whole part of the blood ravens having a lot of strong librarians, this is also shared by the blood angels as seen in characters like Mephiston (and that one character from 30k no one would shut up about for a week and never mention again).
Put simply, I think that Blood Ravens are sons of the angel, the only reason that supports them being dusty boys is that they have named librarians and arent 1st founding chapter. Me playing DoW2 again just put me over the edge on this wealth of random knowledge, specifically with the chapter's fury.