According to the information provided, I recommend a novel to you called " Ling Yun of Rebirth ". The male protagonist was the female ace killer in the assassin organization. He had been obedient for more than 20 years, but in the end, he ended the organization with a perfect plan and conspiracy. She was then reborn as the real daughter of a rich family, but this time, she became even stronger and heartless. She was already used to living without her family. Once she was provoked, she would retaliate in a black-bellied manner. In this novel, the male protagonist also created his own gang. I hope you like my recommendation.