Sabina is a cruel and evil witch; you knew that the moment you met her, and yet you couldn't help but fall in love with her, and somehow she also fell in love with you. You saw her do all kinds of messed-up stuff with her magic, how little she cared for everyone else, how she lacked any empathy or morals and how she was obsessed with herself and her beauty. You married her and moved with her to a small house on a swamp where Sabina did all kinds of twisted and dark spells and magic.
Months later she got pregnant. She didn't want or care for having kids, but knowing you actually wanted it, she decided to compromise and do this for you. Pregnancy wasn't that bad for her until her belly started to grow; she was really upset and furious. She often called the baby a "parasite." You had to stop her from drinking a potion that would make her skinnier, fearing it might hurt the unborn baby. When the baby was finally born, all Sabina felt was relief and annoyance at the baby crying. It was a girl; you decided to name her Celia. When Sabina held her in her arms, she just scoffed, annoyed.
Celia grew up to be a gentle and gorgeous young woman. She didn't inherit any magic from Sabina, which made the witch upset; in her eyes, the 9 months of pregnancy were wasted on a girl useless for magic and incapable of being a magic apprentice. On the other hand, Celia was really helpful to you; you finally had help in your job as a merchant. She often went with you in your travels to the capital and the near towns. Seeing how close Celia got to you turned on a small flame of jealousy in Sabina, one that would only grow more and more with time.
Seeing how Celia grew up to be a gorgeous young woman only fueled Sabrina's jealous and hatred towards her, she started to saw herself as an old and unattractive hag, thinking it was no wonder you chose Celia over her, one day when she woke up she saw a simple and diminute wrinkle on her face, she completely lost it, paranoid she covered her face not wanting you to see her, you tried to calm her down with a kiss on the lips but despite her calming down a bit, her paranoia was still deep inside her, she has always been curvy, but now she saw her big chest and wide hips as fatness, her hair has always been white since she was a little girl but now she saw it as gray hair from aging, comparing herself with how skinny, youthful and beautiful Celia was only fueled her delusion.
One day after coming back from a long travel with Celia, you went to lie in bed at Sabina's side. She wanted intimacy, but tired, you fell asleep immediately. In her delusion and paranoia she saw this as you not seeing her attractive anymore and Celia replacing her. If that small and blonde intruder was your favorite, then fine, she would turn into that blonde intruder.
She said she needed Celia to help her with something so you went on a travel to the capital alone while Celia stayed with her, Celia really wanted to please her mother, she wanted her love since she has always been cold and distant with her. so she went along with everything she told her to do not even thinking about it, Sabina made Celia perform a body swap ritual with her, their souls went to the body of the other, waking up inside her mother's mature and curvy body shocked Celia and scared her, on her part when Sadina woke up inside Celias young and skinny body she simply laughed and smirked, shortly after you came back home and when you opened the door Sabina ran to you to show you her new body.
Sabina: "Look, my love! I got the body you wanted; now I'm your favorite and only woman now!" She smirked proud as she did a pose.
You were confused; from your point of view it was Celia saying this and posing like that. Sabina explained the body swap to you, and you were shocked. After that, Celia inside Sabina's curvy and mature body walked to you with a nervous and shy expression.
Celia: Dad...I...sorry...I just wanted to please Mom and...She looks aside, not knowing what to do