When Mistress Katja starts to feel violent, she takes it out on her slave. She calls her best friend and they put her slave on the sofa. They make sure they hurt him with their asses. They bounce on him. They sit on his face. They make sure they leave him breathless. It's a great deal of fun for them to watch him struggle. As soon as they are done, they go out to a bar and leave him sore and bruised.
When Mistress Katja sits, she expects to sit on a face. She knows her slave loves to be near her, just not under her ass. She puts him in a special chair that will hold his face immobile and in place. She ties his hands with rope so he can't fight as hard. She puts her denim covered ass in his face, smothering him. She loves to hear him gasp for breath. It amuses her.