Mistress Gaia caught her slave wanking in her bedroom and she was not happy with him. She had to make sure he would never do it again so she punished him by inserting her smelly foot in his mouth. In addition, she tied him to make sure he would not offer any resistance to whatever it is she did. She had fun torturing him and he never wanked in her room again.
Princess Serena took her high heel and she used it to teach her slave a lesson. She wanted him to know that she was not going to tolerate any of his nonsense. Her slave was new and his grace period had come to an end. He had to shape up or face the music. So she was giving him a taste of what was to come by trampling him with her high heel and making him lick the dirty soles.