Board Thread:Warhammer 40k General Discussion/@comment-92.97.77.182-20130321145115/@comment-2093048-20140510205930

Some people think that Omegon is the loyalist one and Alpharius is the bad one. Though considering the two can pose as each other, it might not be worth bother differentiating which is which. One crack theory is that Omegon eventually became the first grand master of the Grey Knights, Janus, who's name means "The beginning and the end " (IE, "Alpha and Omega"). It is notable that one in-universe theory is that Omegon was never separated from the Emperor, which, if true, would make him the one primarch who was never touched by Chaos at all (unlike the others. Even loyalist primarchs were touched by it as infants in a way) and thus would make him the best source of untainted gene seed to make Grey Knights from. it was mostly a joke theory but kinda looking more and more valid as more evidence comes out.