I Became The Female Lead's Sister-in-Law in a Childcare

I was reincarnated as a doomed minor villainess in a childcare fantasy novel — an imperial princess destined to obsess over the heroine’s brother, poison the female lead out of jealousy, and die miserably. Determined to avoid that fate, I planned to stay far away from everyone and escape to a peaceful life by the sea.

But after accidentally saving the heroine, everything changed.

Now her terrifying family is obsessively protective of me, the heroine keeps handing me treasures, and even her hostile second brother won’t leave my side.

…Why is everyone acting like this?