I Grew Up As Her Knife

A dying woman can leave a child to a friend the way she would leave property, and the friend takes on the guardianship with it. That is how Ethan Shaw, the only heir the Shaw family has left, ends up in Wendy Chase's house as the legacy she agreed to keep. She sets three rules with him at the start and none of the three are to be crossed. She brings him up hard and teaches him how to move against people, and he becomes the blade she uses on the rivals inside her own family. Somewhere in those years his guard drops and what he wants from her changes. She is engaged to someone else. He knows it and closes on her anyway, one step at a time.