The Emperor found his son. The Sixteenth Primarch: Horus Luprical. Together, they conquered thousands of worlds. Soon, all the Primarchs were found. But… even though the imperial records once stated there were 20 Primarchs, the second and eleventh Primarchs had their statues destroyed and any memories of them wiped by the Emperor. Anywhom. There was one Primarch, Lorgar of the Word Bearers legion. He idolized his father as a god. But the Big E said nuh uh, atheism rocks. So he put him in the time out corner for 15 minutes. Lorgar, being the angsty teenager who now hated his father turned to chaos. Over time something rly bad happened. Remember that the Emperor stole from the Gods, and he never told his sons about chaos to protect them. But Lorgar being the little snot that he was, told Golden boy Horus. Now Horus became emo. He convinced 7 other Primarchs to join chaos. Magnus the Red, master psyker, Conrad Curze, average My Chemical Romance enjoyer. Mortarion, crybaby, Alpharius of the Alpha legion(maybe Omegon as well idk Alpha Legion is wack). Some other dudes and Angron. Angron had daddy issues from the start. But he looks really cool as a deamon. Thus began the Horus Heresy. The only main reason Horus had so much power compared to his Superman wannabe brothers is because Big E made him Warmaster of all humanity. Perks of being the favorite. Also, the Big E didn’t know about this soon enough cuz he was working on the Human Webway project. I’m not getting into that because I already do the Aeldari.