Since there is autistic conversation regarding the Primarchs afoot, I will take the excuse to vomit anuddah autist theory into the thread
The Emperor fully intended for Sanguinius to fall to Chaos and become the Big Heresy Nigga as part of his general masterplan to set the board for the inevitable Heresy ahead of time to maximise his chances of winning, and even directly fucked with his genetics to try and ensure this would happen.
First off, here is a recurring question about every closeted homo in the fandom's favourite space twink. Why does he have wings?
Usually the answer guessed in-universe is some warp fuckery or mutation or even Baal being an irradiated hellhole even by the standards of the setting. However given the fact all Primarchs were dragged through the warp due to
Space Karen taking the kids makes it a lil weird how he got the only such mutation, with only Magnus one-upping him in terms of physical mutations and he was designed to be an extra special snowflake traffic light for the webway project, which could suggest that the wings were part of his design to begin with.
Now why would the infamously reddit-atheist Emperor go out of his way to design one of his sons to look exactly like a biblical angel? And not only that, but also give his planet an explicit pass on the whole religion ban thing as a free concession to him despite being hilariously unwilling to give the slightest fuck about the feelings of other Primarchs and their pre-discovery societies (
exhibit A: ngron). Well...what if he wanted Hawk Boy to become the symbol of religion and religiosity in the imperium so that when he inevitably rebelled and was claimed by chaos he could use this as ultimate vindication and justification to even the other Primarchs why religion bad?
Its been effectively established for a while that Big E knew that some kind of Chaos backed rebellion by a number of his Primarchs was inevitable and was already setting things up to try and ensure that he kept the best on his team while Chaos was left with the barely functional fuckups, ensuring a swift and easy victory for the Imperium. Thus it would make sense that he would designate one of them ahead of time as the obvious leader of such a rebellion, whose fall and defeat would serve his own long term goals, the most important of which being #fuckchristchuds.
To get the gods interested enough to select him as their champion/avatar/joint-fleshlight he poured a few extra drops of his "
special Primarch juice" into Sanguinius's test tube relative to the others, which explains why he has Mary-Sue "kick the shit out of literally every other Primarch" strength and also why he has such charm and charisma even the Traitor Primarchs wont shut the fuck up about how much they respect him and want to caress his sparkly angel balls, and indeed why Horus (
who loudly declared unprompted on several occasions that Sanguinius should have been warmaster guiz) was accurately worried that the gods were planning on replacing him as Big Heresy Nigga with Sanguinius the moment they corrupted him because of how much all four of the gods wanted a piece of his feathery ass to the point they were even willing to share.
Just to seal the deal Big-E also went and fucked up Sanguinius's genetics to not only give him giant symbolic angel wings but also the same "can see his inevitable death in the future" shit he gave another designated fuckup by the name of Konrad, as well as giving him and his legion not one but
two horrifying existential flaws of wanting to simultaneously
murderfuck everyone around them and also
eat/drink everyone around them, to make doubly sure they were even more vulnerable to Chaos corruption as well as hoping to turn his legion into the worst of the barely functional fuckup crews. Also to make sure said legion was ultra-primed for turning on the Imperium, he also ensured that
from the getgo they were given the absolute shittest jobs in the early great crusade in ways that would make Perturabo cringe, all while having their recruits literally be the most diseased and mutated coomers among the Imperium's defeated human enemies he could find.
All in all by the time the Emprah rode up on Baal the stage was set for the IX legion to 110% go traitor out of extremely justified bitterness towards him personally and the imperium as a whole as well as being genetically predisposed to kill and drink people in screaming tard rage, and for Sanguinius to play the part of Archtraitor who also represents fake and gay religion.
The only problem in this plan was that Sanguinius decided not to become the asshole he was designed to be. Worse he even decided to become the galaxy's most powerful kindergarten teacher for the universally despised hate filled flesh eating killing machines of his legion and have them all do fingerpainting until they were happy which somehow fucking worked despite....fucking everything.
Meanwhile thanks to Erebus's Poop Knife shenanigans the gods hastily decided Horus would do as backup Archtraitor instead of the middle management flunky role they were originally intending for him (
which Perturabo would eventually be crowbarred into) and the Emperor spent the subsequent heresy and following 10k years seething that not only was his masterplan to win the Heresy a miserable pyric failure, but that his intended moment of total fedora atheist triumph was stolen and replaced by Sanguinius becoming the beloved Space-Jesus to his new Space-God self.
