Training My PRofessor

She ran her hand around my stomach and up to my right nipple, drawing small circles around it with the tip of her index finger. She pinched it lightly, then leaned over a blew on it. It felt wonderful. She pulled out a metal clothespin, pinched the bottom and clamped it over my now erect nipple. 
"Oh come on, it doesn't hurt that bad. From what I've heard it even feels good. Right, slave!"
"Yes Master!"
She repeated the process with my left nipple. Then she straddled my stomach and leaned over and kissed me. Her hair fell over and tickled my cheeks.
"Let me guess," she said. "You're rock hard right now."
She reached back to confirm it.
"I've known guys who were into this stuff before, slave, but no one who loved it as much as you do. What do you think about that?"
"I don't, Master."
"You don't what?"
"I don't love it."
She brought her hands to the tips of the clothespins and squeezed. I gasped.
"After all I've done to you: all the humiliation and pain, the emotional distress, all the chores and beatings, and your dick still gets hard as a rock whenever I touch you. That means one of two things: either your dick is controlled by someone else, or you get off on being my slave but just don't want to admit it up here."
She tapped her finger against my forehead.
"Don't pout. You're not the first guy to love being a slave. Here, I'll make it feel good."
She turned around and traced her fingers up and down my cock. I sank back and gave in to the feeling. Fighting it wasn't going to do any good.
"Who owns you slave?" She whispered.
"Ohhhh, you do, Master."
"Who do you want to control you, my sweet slave?"
"You Master."
"Anyone else?"
"No, Master, just you."
"Just me what?"
"Just you controlling me, Master."
"That's right slave."
I was going to cum. I could feel it building. It would just take a few more strokes.
Bryn took her hand off my cock.
"Not so fast. We've got a full afternoon ahead of us."
She turned around and removed the clothespins from my nipples. Pain shot through my chest.
"Hurts coming off, huh?"
Bryn smiled. She turned around.
"Your dick is still hard."
"Yes, Master."
"How close were you to cumming a moment ago?"
"Very close, Master."
"And do you know what would have happened if you'd cum without permission?"
"Something bad, Master."
"That's right, so shouldn't you be thanking me for not making you cum?"
"Thank you, Master."
She tilted her head.
"I don't think you meant that."
She picked up the clothespins and reapplied them. I bucked as pain tore through my chest. She turned around and stuck her ass in my face.
"Kiss my ass. Don't lick it. Just kisses."
She took me in her hand. My dick grew to full mast after just a few strokes. Bryn worked me expertly: she gave a couple strokes, then lightly ran the tips of her fingers up my shaft until I felt ready to burst, only to pull her hand away at the last moment. When I calmed down she started all over again. She knew exactly when to stop to deny my orgasm. I lay my head back against the pillow and moaned. Bryn turned and lay next to me. She put her lips near my ear as she kept lightly stroking my cock.
"Slave, do you want to cum?"
"Oh, Master, please! Please may I cum?"
She licked my ear and whispered:
“No.”