Help

I don't know the name of this manhwa is and I only remember a few scenes. What if do remember is that the sister, who's the mc, and brother were drinking tea at this tea party event thing and they were both poisoned through it. The sister is the younger one and I remember she recovered first, to a degree. Once she 'recovered' she helped her brother with her ability. I forgot if she hid that ability from people or not. Please help, thank you ┗( T﹏T )┛