It begins quite simply: Byleth was not with the empire when the church was attacked. She then got defeated and captured and became a sex toy for the empire soldiers. Since she was the Fell Star, an arch enemy that must be destroyed according to the true ruler of the empire, her execution was decided fast ans swift. She was setenced to choose between a guillotine decapitation or be drown by a thousand men's semen. She struggled long time, violated by countless men and suffered, finally decided to let a giant blade cut off her own neck. Her corpse was later sent to the royal capital by the empress's command, except Edelgard herself was turned into a sex toy by her uncle already. The stupid ex-empress was nothing now but a limbless torso and burst into tears when she saw the head of her former professor. Since the Fell Star was no longer a threat, the one who slithered in the dark quickly won the war and built their own regime, became the only ruler of Fodlan, hence no former royalties in Fodlan were necessary anymore.
Edelgard's execution came in her bed chamber, performed by her uncle Lord Arundel by slicing her neck with her precious dagger while having a French kiss with Byleth's detached head. Lord Thales used his enormous giant penis to fuck through both Byleth and Edelgard's heads, and with the assistance of Lady Cornelia he even stuck the tip of his dick into the neck hole on Byleth's headless corpse. It was rumored that such a giant monstrosity once easily stuffed a girl's entire neck to her lung and suffocated her, but it means nothing to the lifeless victims now except for some simple nerve reflex throat gagging and body twitches, proving both Edelgard and Byleth had been transformed into pure onaholes for pleasure. (Yes I was told that in Three Hopes it has been proven Arundel is Thales himself in disguise. But I think there's no direct evidence from Three Houses to prove that. Plus it would be much hotter for an uncle to execute his sexy and stupid niece, and if we don't use Thales and Arundel at the same time there won't be anyone famous from Those Who Slither In The Dark, right? Would you like to watch the old man Solon to fuck Edelgard? I wouldn't, really. )
Lady Cornelia had ambitions and began willingly cooperating with Lord Thales and Arundel long ago and used her beauty and magic skills to work with them. Her newest research had succeeded in necromancy in the form of manipulating dead bodies. Combine with Agarthian technology it became a skill to keep dead people partially alive and obey its master's wishes, and it quickly became Thales and Arundel's favorite skill. Cornelia helped them to make many living sex dolls, and layed with these corpse together with the lord for pleasure. But of course, as a human, she could never be trusted by the underground regime. As this moment the last empress dies, Cornelia's assistance were no longer required in the war. So she was decapitated on the spot as well, as a climax entertainment of the night.
Unexpectedly, Cornelia was such a whore. Even after countless nights of being thrust by Thales' giant cock, she was ever more eager to experience extreme sexual performances. To have a taste of decapitation, and become a neck-hole fuck meat herself is actually a secret wish for her. Unlike the other two girls, her users later found her (and her body) being weirdly happy, proactive and intoxicated in the head fucking business, as she was really enjoying it. It was quite different from Byleth and Edelgard's heads, who resisted constantly even in death, and required brain surgery to stimulate their orgasm core to tame. But all of the three bodies worked properly under the control of magic and technology. The mindless bodies have always behaved willingly and obediently to have any kind of sex the masters want, and they are always horny without the instinctively repression from their heads: people even witnessed them touching, rubbing, and kissing each other with the neck stumps even while no masters were around.
Perhaps the rule of the underground people would bring a brand new culture to Fodlan, we'll have to wait to see the fate of other girls to discover more.
Somehow, despite all the content, it’s the complete lack of understanding of the lore that bothers me the most about this. Guy understands enough make excuses about Thales not being Arundel, but doesn’t also realize that Cornelia was an Agarthan too? I mean, it wasn’t even particularly hard to understand in the original, much less Hopes!