How Do I Deal with My Picked-Up Junior Brother Being the Villain?

[My Life as the Devil's Master After Transmigrating into a Book has started next door. The blurb is at the end] After Shen Yu transmigrates into a book as the villainess, the one thing she wants most is to find the demonic cultivator who will torment her until her soul is utterly destroyed. If she finds him early, they can become brothers or best buddies, or... if they can't see eye to eye, she can take him out before he gets powerful. But when she finally finds the villain, she discovers that he's not quite what she imagined. She can't put her finger on what's different, but the more time passes, the more he reminds her of someone... · Everyone in the sect knows that Senior Sister Shen of Luodan Peak has been searching for someone. "Junior Brother Ji, give it a rest! Senior Sister is beautiful, talented, kind, and powerful. Why would she ever be interested in you?" "Look at yourself. You've been following her around all these years. Has she ever paid you any attention? No!" "If you ask me, Senior Sister would never like you!" The words of the people nearby stabbed at Ji Xiao's heart. A frenzied, violent force roared in his mind. Eyes bloodshot, he forced it down, then jerked his head up and bellowed, "Shut up!" You know nothing. How could you possibly understand? · Later, Shen Yu realizes that the junior brother she picked up seems to be getting stranger and stranger. Before she can think it through, he hands her a jade pendant, his voice trembling as if he is holding something back. "Senior Sister, this magical treasure was left to me by my mother. It might help you on your journey." "Senior Sister, are you going to look for that person again?" "..." Why does this pendant look so familiar? Shen Yu: You're the big villain?! [Male lead: I'm jealous of myself.] [Repressed demonic aura, loyal puppy x carefree senior sister] Reader's Guide: This is not traditional cultivation fantasy, but low-magic xianxia! No monster-slaying-and-leveling-up plot! The worldbuilding is entirely made up, made up, made up! Don't overanalyze it. Slow burn. Lin Bei wakes up in the body of a cannon-fodder villainess who has just died in a Western fantasy novel. The magic circle, which was about to disappear, is completed by her soul. She summons a feathered creature, black as night and neither bird nor beast. Its red eyes regard her with malice. At night, the black bird transforms into something strange. Its body is shaped like a human's, yet not a single part of it is human. Its features possess an eerie beauty, with a pair of horns on its forehead and black wings on its back. He calls himself a demon. · In the middle of the night, the demon takes human form for the first time and suddenly grabs her hand with his enormous claws. He lowers his head and breathes warm air beside her ear, tempting her with malicious delight: "Human, offer me your soul, and I will grant you eternal life and beauty. Wealth and power will all be yours." Lin Bei kicks him away. "Watch your tone. Call me Master." Theme: Face your inner fears. Solve problems instead of running away from them.