괴물 대공의 시한부 동생을 숨겼다 (Associated Names)

I found myself transmigrated into a novel full of obsession and tragedy, but I didn’t care one bit. I was neither the heroine nor the villainess; I was just a passing noblewoman. I felt a bit of remorse for the heroine, who would rescue a child and suffer at the hands of the villain, but…