Just an idea for now. I'll write it properly later.
Elizabeth Hanover treats getting close to Lord Voldemort as an exciting game. As a favored daughter of heaven, descended from the rulers of Britain, she has ample confidence when it comes to teasing that seemingly dangerous man.
Tom Riddle lets Elizabeth get away with her pranks. Of course, this rare good temper stems from an arranged marriage that is about to take place, just as he planned.
* The author plans to write a very new kind of magical-world CEO romance.
* An alternate universe setting. You'll meet a more rational Dark Lord.
* In 1917, George V changed the royal family's surname from Hanover to Windsor to make the royals seem less German. The heroine is a member of a collateral branch of the British royal family who kept the Hanover surname.
Theme: Marriage is a man's second chance at being born