Mistress Isabella Tasci realized that this guy wanted to fuck her. When she found out more about him, she realized there was something she could get from him too. She chose to make it a mutually beneficial thing but she had to get what she wanted first. And once she did, she could not see herself fucking him. Instead, she got him to lick her feet and she gave him jerk off instructions which he used to cum.
Mistress Isabella Tasci wanted to show her slave how it is done. She caught him masturbating and he was doing it so pathetically that she felt pitied him. She even offered to tease him a bit to help him get off. She used her sexy legs to do it and she teased him playfully and told him what to do to himself and he did it and it was magical.