Board Thread:Warhammer 40k General Discussion/@comment-6078851-20130318203252/@comment-6078851-20130328003100

to expand on your long shot marshall - let's say that horus was indeed in the past and the emperor saw him, but maybe his sight was obscured by the warp energies in the room. hey-ho, years pass, emps reunites with his kiddys, and when he meets one of the 'lost' primarchs he mistakes him for the being he saw in his labs when the tanks were scattered. possibly reason enough for the emperor to sic the wolves on him and then deletion from imperial records?

i'll stick with the vision opinion but this one is interestingly plausible :)