Herself

"I could do it. I have a worked with a number of individuals with submissive tendencies in the past." Dr. Vierre didn't say that she had often been their cause. "Unlike some stranger, you would also not have to worry about them getting overzealous. You would be in complete control as to how much control you ceded to me."

"That sounds perfect." Mrs. Lewis said. "But my son won't hear about this, will he?"

"Absolutely not. The contents of your sessions with me will be entirely confidential. Of course, before we start, I will need you to sign this form, and tell the level of sexual activity that you would like to have."

"...Sexual activity?" She sounded nervous.

"Oh, yes, this is a sexual fantasy, right?" Mrs. Lewis nodded. "Then you need to indicate how far you'd be comfortable with me taking you, on a scale of one to five. For instance, groping, nudity, that sort of thing."

Mrs. Lewis considered how comfortable she'd feel about various possibilities. Eventually, she picked a number.