This mistress wanted to advance in her career and she felt that since this guy was the one holding her back, she had to dos something to him in order to get him out of the way and stop him from being a hindrance to her progress. That is why she chose to torture him in a way he had never been before. And she used her shit to do it.
Mistress Nemezis wanted a portable human toilet for herself and she turned this slave into one. She did not like how he behaved and the mistakes he made so she did what she does best and he changed after what she did to him. He never messed with her again after that. He had to suffer the indignity of being used as a human toilet and he had himself to blame.
This guy was a spy but he did not think that this mistress knew. She knew and she was waiting for the appropriate time to strike. When she felt that the time was right, the mistress used her shit to put him in his place and torture him the way he was supposed to be tortured. He had to eat shit and drink pee as well as do other cruel and degrading things.