User blog comment:WhiteSeraph/Alternate Timeline Idea That I'm Really Psyched About/@comment-3341288-20110929013202/@comment-25033299-20110929032348

I think the best way to go about that is by having the Emprahh tell each of the primarchs about Chaos at the same time that he finds them. Basically a "I'm here to unite you and to warn you about this prime evil" kind of thing.