He believes her

Shila took in his face, staring up at her vaguely, like he was trying to take in everything about her at once. His eyes had given up deciding between her tits and her face and settled on being content with the whole picture. She knew she had him when she took in the look of pure lust and desire, like she saw from almost every other man in the world who saw her, clothed or otherwise. His expression had been so cocky just seconds ago, like the world belonged to him, and now he was so obviously just another man before her immeasurable sexuality. She felt like a predator, who had just caught the most cunning prey she had ever met, and can't help but grin, showing her perfect white teeth between her plump painted lips.

"Wouldn't you?" she repeated, since it was obvious he had lost all focus on her question with her body on display before him.

He gulped. Perhaps John had gone too far. Perhaps he had wanted this the whole time, but now he didn't care whether he had or hadn't. He took in the sight of pure sex before him and believed her. He absolutely would do anything she asked of him in hopes that she would fuck him. No, he would do it regardless, because _she_ asked him to, and she deserved whatever he could give. And his belief made sure that this was true, triggering whatever it is in his brain that makes the world fit to his desires. There is nothing in the world he wouldn't do for her, and nothing could break him of that belief because it reinforced itself through his power.
"Yes," he breathes when he can finally speak, maybe seconds or minutes after she asked the question. He is too lost in her to know how much time has passed.

"Good, then what can you give me?" She asked, climbing up on his lap, settling a knee on each side of his thighs, the tent in his pants nearly jabbing her in the crotch, exposed by her tiny skirt made even smaller by her legs spread so far apart. She wrapped her arms around his neck and pressed her tits into his chest, more because of their size than because she needed to make contact to bewitch him further. He was already wrapped around her finger.

"Anything," he said, his voice nearly hoarse.

"I thought we established that your powers were an illusion?" She said, some of her old therapist instincts creeping back in. This was about her now, but she couldn't help but want to treat him and his delusions as well.

"No, you have to believe me. I'll give you anything and everything!" he said. In his desperation he pushed his powers at her. He didn't want to change her, the being of perfection that she was, but she had to believe him so he can help.

As her mind shifted and she was **** to believe him, Dr. Shila gasped. "Oh, I see," she purred.