Forced to Marry the Regent

Transmigrated into a book as a side character whose family is annihilated, Nia Everhart is slapped and has her engagement broken by The Crown Prince. Bound to a system, she faces sudden death if she doesn't kiss the mad dog eunuch, Caspian Hale. To stay alive, she publicly forces a kiss on the fake eunuch, the Lord Regent. This unhinged villain is moved by her advances. She saves his family, rewrites her fate, and he kills the emperor, seizes the throne, making her his empress.