This mistress needed to dominate and to punish this slave because he was slow and she was tired of always telling him what to do. She did not want that to continue to be a thing and so she used her fighting fetish to deal with him. He cried and begged her for mercy but she did not stop as she did not want him to take anything for granted.
When this guy wronged these mistresses, he took it for granted and he thought that he would get away with it. But he did not and he had to endure all that was thrown at him. He had to do what the mistresses wanted and that is how he found himself being ballbusted by the mistresses who did not care about his pain but had to teach him a lesson.