2, Bob and his lore edits, starting with the missing Primarchs

As he was creating his version of 40K, Bob gave himself a few things:

• Insane luck
• Protagonist plot armour protection
• An innately attractive visage and personality for everyone who looks at, sees, or thinks about him
• A super soul with more Warp powers than the Immaterium (Broken, I know)
• A version of psychic paper bound to his being, providing him with documentation wherever he goes

With these assurances, Bob began to mess with the story by filling in the spots of the missing Primarchs. The second Primarch became Bimbosa, and the eleventh Primarch became Femme Fatale.

Bimbosa:

Bimbosa landed on an advanced world that used to serve as a medical and science hub for 70% of Humanity's healing-related professions and advancements. She quickly found herself having a sexual awakening, crossing over from her male form to a female one before picking up ancient bimbo styles, getting herself intense hormone shots and plastic surgery to become a perfect little bimbo. Also, since she was a Primarch and her body transcended ordinary men, her crossing of genders was something her body could accept, creating a hybrid geneseed that carried eggs, gender-bending the male space marines. As for women, since Bimbosa had this special effect, she could create female space marines, though at the cost of impregnating the female space marines with exceptionally virile geneseed-sperm-eggs. These women would need to be impregnated regularly to maintain their form since a space marine female without a child would lose the hormonal boost that pregnancy gave her, which made the women stronger and bigger than their male counterparts. The female space marines would still be space marines, but they were innately superior to males, with any damage to their pregnant bellies only hurting the babies inside. As for how they did this practically, the female space marines would be escorted to densely-populated areas where the whored themselves out for their own pleasure and that of their reproductive instincts. The female space marines are vastly superior to regular women so, since their pussies work, they are also super fertile, enabling them to get pregnant while pregnant. The gender-bent male space marines would often accompany the female space marines while they did this task, setting boundaries and ensuring their sisters didn't have too much fun and accidentally pop a guy with their thighs. On occasion, this usually meant that the accompanying gender-bent males ended up joining the fun, bringing their more masculine charm as opposed to the feminine or bimbo charm that the naturally female space marines brought. The gender-bent male space marines weren't as fertile as the female space marines, but the guys they really liked could be picked out to have their sperm artificially inseminate the gender-bent male space marine's womb, or the pair would get lucky and get the gender-bent male space marine pregnant. When that did happen, the gender-bent male space marines were more reserved with their pregnancies and had them less often, so they were usually very careful but always made sure to hide and strap down the foetuses as much as possible.

The change was weird and fast; Bimbosa left no room for doubt as she offered her space marines the choice to improve themselves with her new geneseed. Her sons loved her and welcomed her rule, but her form gave them an uneasy feeling, watching in bewilderment and slight disgust as she showed off her enhanced female assets, which were made way bigger once her body accepted the change. As would be expected, although a lot of space marines loved their father-turned-mother returning to them, they didn't want to change their genders and turn into plastic Barbies with pillowy lips and seductive poses. This led to a split of Bimbosa's legion upon her arrival, dividing her troops amongst her brothers or simply integrating them with Bimbosa's new space marines. To see a male space marine in her legion who hadn't recently transferred in from a segregated space marine battalion meant they were old and experienced, having survived the many years of campaigning across the galaxy. Not many were left since those who didn't go in a segregated battalion of Bimbosa's old geneseed had undergone the new geneseed implantation or died in battle. Still, these men stood out strongly, adopting some of the practices of their battle sisters, like taking romantic partners with them across the stars, even if only in a loving, celibate capacity.

Their legion was known as the Plastic Bimbos, a joke name with some real significance since it correlated to Bimbosa's existence. Their chosen method of conquest involved peaceful exchanges, where the Space Marines would use their unnatural charms to seduce influential and important people. Once they did so, the men who were ensnared would be transformed into females and get pregnant while their Space Marine lover carried their child. The changes wouldn't be immediate, allowing the Space Marines to utilise the captured individuals to grow nests of connections so they could eventually overthrow the ruling powers. This wasn't always viable, especially against aliens, so they often had to resort to simple conquests using conventional Space Marine strategies, mixing in their trademark tricks when doing so. Additionally, their legion's standard battle style revolving around impregnation created an incentive to find a way around species barriers. The resulting research was an additional organ implantation that identified reproductive markers in the species they're pleasuring themselves with. Theoretically, if a Space Marine's vagina could stretch far enough, and if the Space Marine could pleasure both themselves and the machine spirit, a Space Marine could get pregnant with an Imperial titan. It's not true reproduction; it's more like the additional organ creates a reproductive algorithm by analysing the individual the Space Marine is fucking, creating a corresponding DNA strand to mix with the mother's. In this way, Space Marines from the Plastic Bimbos legion can romance and reproduce with aliens, sometimes birthing human children who're able to reproduce with the alien parent's species.

As for why she rebelled, she wanted peace not war and Femme Fatale's legion gave the best orgies.

Femme Fatale:

Created as a Blank, Femme Fatale is a futanari warped by the Immaterium during transit to her new home as a baby, giving her a functioning pussy and cock. As both a futanari and Blank, Femme Fatale felt incredible discrimination as she grew into the **** futanari-archetype, finding solace as a young brothel worker who got abused by men. At the same time, they fucked her without a care in the world, spitting on her and making her do other nasty things while they abused her. But when Femme Fatale finally got to use her cock on more than her hands, she found a way to cope with her lacking love life. By using her massive and pleasing dick, Femme Fatale grew her confidence whilst she formed a legion of submissive women wanting another pounding. When the Emperor came, FF controlled her world, impregnated every woman, and created a gender-based caste system where women lovingly worshipped the cocks of FF's futanari children, feeding men the semen literally pouring out of every building, requiring special canals and pipelines that women went diving in to get themselves a beautiful futa baby or feed the non-futas.

Upon getting her legion, FF immediately started pushing her non-futa Space Marines into extra and hazardous roles to keep up the slack whilst FF started pumping out futanari Space Marines. When FF believed her futa Space Marines reached a satisfactory number, she finally backed up her male legion members, leaving them humbled as the futas showed superior strength and speed, as if FF fused an Eldar's speed and flexibility with a Space Marine's strength. FF then sealed the deal using the virility and NTR power of her futas, spawning a large percentage of people looking up to their Primarch matriarch/ancestor. Correspondingly, it was no surprise that most of FF's worlds defected and her sons stayed loyal when she rebelled.

As for why she rebelled, the heinous acts going ignored when it came to regarding her kin were simply unacceptable.