This slave needed to be put in his place and this mistress made sure that it happened the way she wanted it. That is why she chose to use her feet to do it. He had to be trampled, stomped and to get all other humiliating things to be done to him. The guy could not believe what the mistress did to him and he had to do his best to change.
This mistress had a lot of time on her hands with nothing better to do with it. That is why she chose to play with her feet. She had a thing for foot fetish even though she had never explored it. Today the mistress had the time to do so and she took out her video camera and she recorded herself as she tried it out for the first time.
When this mistress noticed that her slave was tired all the time, she tried to take stock of the work he did to see why he was tired. But she realized that he hardly did any work. His tiredness was out of his laziness and she could not believe it. She humiliated him with her feet by forcing him to lick and smell her stinky socks and promised worse if he did no stop his laziness.
Mistress Zephy was pissed at this guy and she knew it was up to her to dominate the loser and do it as cruelly as she was able to. She did not hesitate to beat up the guy and she did it with her feet which he had to lick before she used the same feet to trample him. He learned his lesson and he got the message she wanted him to get.