Princess Serena was in the mood to humiliate and to have fun. She chose to do so at the expense of this guy. The mistress is blessed with a sexy ass and she used it to turn on this guy but she did not let him smash as he thought she would. All that happened was that he was left high and dry. She pretended she had to go and attend to an urgent matter after teasing and denying him.
This mistress caught her professor checking her out. She became observant over the next couple of days and she realized it was true that he was indeed checking her out. He was in love with her ass and so she used it to get good grades in his subject. The mistress found ways to tease him and control him and without him knowing, he favored her in tests and she passed with flying colors.