I recommend a book to you,"The Trash Prince and the Killer Concubine". It's an ancient romance novel. The female protagonist is the head of a modern assassin organization. She accidentally transmigrated to the royal world and became the concubine of the Trash Prince. In the beginning, the female lead did not like him and thought that he was very boring. But later on, she gradually realized that she had fallen in love with him. The male lead was an unfavored prince. At first, he was a good-for-nothing, but later on, he became more and more outstanding. In the end, he became one of the forces and turned the fate of the royal family around with the female lead. I hope you like my recommendation. Muah ~