Lady Phoenix was out to make sure that this guy learned his lesson and she used her gas mask to dominate him. She farted into it after he had worn it. She then had fun seeing how he choked and she had a great time at his expense. The mistress even punished and humiliated him more than was appropriate. But that was because it became more fun and she forgot why she was doing it.
Mistress Delvia and her friend lady Phoenix had a slave who was misbehaving and he needed to be tamed. So the mistresses had no choice but to punish him and make sure that he would never do that shit again. He was made to smell their farts as a warning before they warned him of dire consequences if he did not change. He changed as he knew they meant what they said.