Mistress BlackDiamoond had always wanted to humiliate this guy. And now she had the chance to do it. She did not waste the chance. She instead turned on the guy and she got him under her control. She enjoyed making him lick the soles of her boots. She made him lick them even after she had spat on them. She lied to him that it turned her on when he did that.
Lady Karame had sent her slave on an urgent mission. But he was late and she did not like it. She did not want him to be late again so she used her boots to punish him. She got the boots dirty on purpose so that she could use them to humiliate him. She degraded him by asking him to lick them and he had no option but to do it.