Lady Emerald likes to enforce discipline in brutal and cruel ways so that one does not repeat it. That is what she did to this slave because she felt that he was becoming complacent and she had to stamp out the indiscipline associated with him. So she whipped him mercilessly and he felt pain he had not felt in a long time. He was tied up so that he would not resist.
Mistress Lyla wanted to try extreme whipping. She had never tried anything as extreme as that and she had to do it today. She summoned all her courage and she did it. The mistress had to wait until this loser messed up before she did it. She did not want to feel guilty. So after he had messed up, she asked him to undress and after he had, she whipped him brutally.