They’re not siblings. The Fl is a possessor and the body she’s in is the daughter of the Ml’s father’s friend/unrequainted love. Yes they did grow up together for a time, but she ended up spending like 10 years or so living on her own in another territory after getting kidnapped and had no contact with Ml because of the father’s interference.
If u read.. In this setting.. The nobles have a culture where they "adopt" a child from another family that they intend to marry to their own child.. So in other words usually the child from other family that is brought to their home is an intended fiancee of their child.. There are also adoption as in the literal sense of it too..
1.But for outside people they always thought Rachel was brought in as Lucia fiancee.. 2.The former Duke brought her because she is an ex lover's child. Always see her as that although he always want her to feel like he is a father figure. But parent in laws can also have that familial feelings towards their son/daughter in laws..
3.Rachel, just tryna be good without developing strong attachment in order not to be killed, hurt or disappointed. So she try not to think of them as family but as a means of survival in that world. As a good person who may throw her out.
4. Lucia develop obsession as she is the first to show him compassion and made him feel loved
Therefore, their relationship does not give off any incest connotations if that is ur stand for hating this.. This reply is written in order to deliver or share some clarification on some matters about the manhwa
the promo was icky, they’re literally siblings im gonna throw up