Transmigrated and Accidentally Saved the Villain

[Character development + plot-driven + groveling for forgiveness + twists] Resilient, clever medical student × gorgeous, tragic, seemingly innocent but secretly ruthless Demon King Medical student Su Yunxi transmigrates into a cultivation novel and saves Xie Zhixuan, a “poor little thing” who has been badly injured. She gives him all her medical skill and tenderness, keeping him behind her and healing his many wounds. Until he drops his disguise and crushes his enemy's skull with his bare hands, then laughs softly in her ear: “Big Sister, now it's my turn to protect you.”