User blog comment:Primarch11/Guilliman Heresy/@comment-1436455-20120616071138

I got your alt-Heresy idea right here: none of the Legions go traitor. Instead, regular people get tired of being dwarfed and dominated by superhumans. With the aid of the Adeptus Mechanicus, they turn on Empy and the Space Marines. The Emp's ego takes a big hit and he's initially unable to take direct action against the rebels, since he always considered himself to be acting in the best interests of mankind and now mankind's turned on him. The Legions all take different approaches to dealing with this revolt as befits the character of their Primarchs. DISCUSS.