This mistress has a lovely ass and she knows it. She has a lot of admirers as a result and today she wanted to take advantage of one of them and degrade him to see what power her ass held over him. So she teased him and when he had been turned on, she made him eat her shit and the guy agreed to do it and she was shocked.
Mistress Isabella loves her tradition of shitting on new slaves and she did not hesitate to do the same to this slave. She did it as a way to test who could stay and who would not. It was also to send a message that if anyone wronged her, he or she had better be prepared for what she was willing to do to him as revenge. The guy passed the test.