He grunted and groaned as she cleaned him of the last bits of semen. With one last suck, she let him pop out of her mouth audibly and smiled, cum stre...ked and happy. “Who do you belong to?” he said, positioning her head up and keeping her locked in his hands. She smiled wider and answered, “I belong to you, Sir. Always.” He growled quietly and said, “Good girl. Rub the cum into your skin.” He released her and she began with a thumb across her coated eye. She did her best to recover as much. I was shaking in anticipation and humiliation, waiting for him to say something but he didn't. He just looked at me with a sneer. "Well here goes," I thought to myself, "I have fantasized about it." I never considered walking away because of how ugly he was. Instead blushing with humiliation I dropped to my knees in front of his limp old cock. "That's right bitch," he said, "suck that cock." I could feel my face burning with shame. I could just walk away, or tell him not to talk to me like. She was in pain and didn’t stroke her. Then when her pain was some less she asked me to stroke her. I did it slowly then I increased my pace she was moaning. I loved this act. I pushed it more n harder she was struggling with pain but I showed no mercy and even put my hand on her mouth so that no one could hear her. She bit my hand. But I didn’t stop she cummed but I still provided her the strokes. She begged me to leave her but I insisted & said i’ll not tilli also cum. Soon I also cum and. "Good, lets get cracking just as soon as we can find a free minute," I said with a big smile.It was fairly easy, all the kit and chemicals were readily available from the university stock, it just took time to set up. It resulted in a clear liquid that had no affect on our female lab assistant. We used as a delivery method a glass of red wine, that we had added the clear liquid to, after making sure that that our concoction was non-toxic of course. So it's was back to the drawing board, in this.