In the novel Blue Picture, the main reason why Master tortured the hostess was to exercise her and make her strong. Master understands that the hostess has the heart of revenge, but she doesn't have enough ability and experience to cope with the complex challenges in this world. Master hopes that through torture and challenge, she can inspire her deeper strength, make her persevere in the face of difficulties and adversity, and finally achieve the goal of revenge successfully. Although this process may be difficult and painful for the hostess, Master thinks it is necessary and the best exercise for her.