The Genius Heir's Vengeance

Quinn Hall is the Hall family's real daughter and an IMO gold medalist. But her biased parents, brother, and fake sister Avery set her up and threw her into juvenile detention. Three years of hell broke her mind, birthing Raine — a second personality with the wits to destroy everything. Only her late foster mother's music box keeps the monster at bay. Quinn comes back quietly, only wanting to graduate. But Avery never lets her be: burning her books, wrecking her meds, and crushing the last music box. The Halls have no idea — they’ve just unleashed the devil who will burn them all down.