Mistress Sofi wanted this guy to learn that she was not his equal and that she would not take any nonsense from him. So the mistress made sure that she dominated him with her bare feet which he also had to lick. When she was done with him, she asked him to suck her toes and when he finished doing that, the mistress had him rub her feet until she fell asleep.
Mistress Kira did not think that this slave could be dumber than he already was but he shocked her. And she did not want to let him continue being dumber than he was. She had to make sure that he tried to better himself. So she used her high heels to trample him and she also spat on him. She wanted the humiliation and pain to help him change for the better.