Mistress Nica came from horse riding and she punished her slave by turning him into a human horse. She rode his back and she dominated him and made him feel a lot of pain as she nearly broke his back. His back was not used to supporting such loads and that is why he felt a lot of pain and he cried for help as she smothered him and rode his back.
Princess Serena wanted to hand smother this loser so she did it cruelly for her own fun. He had not even pissed her or done anything to her. They did not even know each other and had never met. But she felt the need to punish him and she did it cruelly using her hands. She also choked him using her shoes. He had to lick her boots even though they were stinking.