FL was purchased from a s*ave trader with her limbs broken, face destroyed by branding, whipped all over, and was supposed to be mute as well. It turns out this happened because her sister ordered it, initially because she was jealous over a guy, later revealing it was because their dad had the nerve to want to treat the FL well and find her a decent marriage and have a dowry equal to hers. Essentially she was bitter because... she was being forced to marry a prince and live an imperial life with concubines around. Not the FL's fault (and usually the dream marriage in every other C-novel), but ok. So having never showed signs of being such a vicious person, she leaps straight from "good girl" to maliciously destroying her sister and not being sorry about it. I guess the servants are all s*upid too, because they helped her (surprisingly, "she told me to do it" isn't a good excuse when you explain to the PM why you helped his elder daughter sell the younger one into s*avery). Then when confronted by her father and punished, her response is to be unremorseful and spitefully... hang herself. Yup. That will show them.

Her father is the Prime Minister and was deeply in love with his wife. The wife's cousin was in love with her, so while she was heavily pregnant he drugged the PM and another woman, then had the wife come upon them having s*x. The wife goes into early labor, and the cannon fodder other woman gets pregnant and hands over the baby for them to raise because they can provide better for her. The wife is a genuinely nice person and doesn't harm the OG FL, but also understandably does not act as her mom. She does not lack for material goods, but is separate from the family.

Somehow he's just a genius (no, having a genius parent does not make you automatically smart, but whatever). He finds out that his father was from a noble family, but left after another crazy drama 🙄 You see, his younger sister fell in love with him, but knowing it was wrong, kept it secret and agreed to marry his good friend. On her wedding day she dressed up and then... hung herself. Yup. Another crazy girl. The family found her stash of secret love letters and paintings of her brother, and the grief stricken mom blamed him, everyone else was busy comforting her, the groom-friend cut ties, and he left, never to return. The family regretted it, but never found him, and he died in a s*upid cave collapse while on an unsafe hunting expedition in the mountains (really, hunting a boar is no joke, having more people does not mean you can catch a boar without specific weapons).

After the su*cide she is... brought back by the FL's magic space (that's never explained 🤷🏻‍♀️) but her soul is replaced by the FL's assassin trainer in her previous life. She is perfectly happy to accept the punishment that the OG sister deserves, in exchange for a peaceful and luxurious life. She ends up killing the prince fiancé in a very torturous way, because he tried to ruin her reputation by drugging her in a very s*upid scheme. The author really lacked logic here. Her family would NOT be grateful to him for marrying their daughter after she's ruined, if the prince is the one that arranges her ruination. And yes, her father would find out even if she didn't tell him, because it's a very obvious plot and he's the Prime Minister, not some naive guy. Anyway, that kicks off the sister's story and her own romance, which was its own pile of drama.

Each of them cut ties, the FL acknowledging that her father DID care for her but "not enough." I'm unclear what she expected him to do beyond disciplining the sister - which he unhesitatingly did. Even his wife condemned her daughter for being so vicious and treated her fairly. FL understandably wanted to kill her, but it's not remotely realistic to expect the parents to do so. Particularly when FL returns the day after their dad found out what happened, and is completely miraculously healed from her injuries. So he never even sees the result of what her sister did. The ML decides that his dad cut ties with his family because they were unforgivably terrible to him, and since the father never mentioned them, he wouldn't recognize them either. Never mind that the family was in turmoil at the time because of his aunt's sudden su*cide, and that not all members blamed him. His cousin had been practically raised by him for years, but the dad leaves them all behind. I just don't find either family to have transgressed enough to cut them off when it hurt them so badly. I mean... having more family (particularly powerful family) is usually better...