I Became the Villain's Accessory [Transmigration]

Ji Yan transmigrates into a Mary Sue novel as the male lead's villainous sister—a mortal weakling in a world of cultivators. No spiritual roots, needs three meals daily, and gets winded climbing stairs. When righteous sects offer her as a sacrifice to the bloodthirsty Demon Lord Yin Xuezhuo, she expects death. Instead, a mysterious System binds them together: he must stay within ten steps of her, shares all her pain, and dies if she does. The furious Demon Lord is now stuck babysitting the most useless human alive. "I'm hungry." "I'm sleepy." "I think I caught a cold." His threats to devour he…