Madame Marissa had a free day and she did not have much to do on that day. She felt that she had to dominate this guy and she had to do it as a way to entertain herself and as a way for her to make him get scared of her and be obedient always. She had him lick her sweaty and smelly feet and it was all for fun.
Madame Marissa wanted to pass a message to this guy and she did it with her boots. She used them to trample and dominate the guy. He was in pain and he tried to beg her to stop but she did not stop. Instead, she went ahead to dominate the guy and humiliate him like never before. That is how he learned never to piss her off and he learned his lesson the hard way.
This slave thought he knew it all and he tried to do things his way and not the way madame Marissa had instructed him. He ended up messing and since she had warned him, it was now time to punish him and she made sure the punishment was cruel and that it led him to realize he can never ignore her instructions again. He learned his lesson and they never had issues again.
Madame Marissa wanted a foot rub so she asked her new slave to give her one. But she did not like the way he gave it to her and she told him. He did not improve much and she did not want to waste her time. So she punished him by humiliating him using her bare feet. He had to lick them now instead of rubbing them the way she wanted before.