After I Transmigrated Into a Book, the Big Bad Spoiled Me Rotten

(Fake transmigration into a book, everyone dotes on the heroine, fantasy, lucky koi) Yun Guiqian transmigrates into a book, becoming... the cannon-fodder supporting female character in a fantasy novel with a female lead that she'd read. In the book, she's just a supporting character who foolishly covets the male lead. She appears three times before meeting her end. Yun Guiqian: Speechless. To avoid her tragic fate, she decides to stay far away from the leads. Who knew the heroine would come to her first, and that she'd end up doted on by a whole crowd of big shots? Heroine: Qianqian is my bestie. Picking on her is the same as picking on me. The heroine's underlings: The boss's bestie is our bestie. Nobody gets to bully her. Male lead: My wife's bestie is my bestie. Let's see who dares bully her. Even the book's great villain, the Demon Lord, starts orbiting Yun Guiqian. Onlookers: She's your bestie too? Great villain: No, she's my little ancestor. Yun Guiqian brings home a beautiful little waif. At first, she just thinks that if she dies one day, at least someone will be there to bury her. But later, she finds herself safe and sound, while the waif's gaze grows more and more unsettling. When she finally learns he's the book's great villain, she tries to run, only to be caught and dragged back. Great villain: Qianqian, where do you think you're running? Yun Guiqian: *sniffles* (´;︵;`) The great villain, Yan Beici, grew up without parents, suffering abuse at the hands of others. After becoming the supreme ruler of the Demon Realm, he grew volatile and killed without batting an eye. Then, after a sudden fall from power, he became a helpless little waif with no strength to defend himself, and Yun Guiqian took him in. At first, Yan Beici: Once I regain my true form, I'll kill you. Later, Yan Beici: Qianqian, don't send me away. This story is also known as Everyone's My Bestie After I Transmigrate into a Book.