What you want to ask is what is the real relationship between Liu Lang and Liu? The real relationship between Liu Lang and Liu is father and son. In The Algorithm of Justice, Liu suddenly appeared as Liu Lang's father. After inquiry, Liu said that Liu Lang was his father and chased him to a law firm. Liu took out a piece of paper from his bag and gave it to Liu Lang, which said that Liu was indeed Liu Lang's son. So the real relationship between Liu Lang and Liu is father and son.