Gruber's Volunteers

Evaluation

The sessions passed one after another. After each round at their machine Anna, Chris, and Beth left so exhausted they had to be carried to their rooms. After a while they blended together and their bodies were left in a constant state of tension and release. They were exhausted, but the sadistic doctor clearly had an agenda. They had all noticed changes in each other as well. Anna’s organs had grown noticeably, as had Chris’. All of them were much more responsive to touch sensations and their orgasms had grown increasingly intense; more intense than any of them had ever imagined possible.

It was impossible to judge which session they were currently on, but following restraint in their respective devices, the three were shocked when they didn’t start up like usual. Instead they saw Gruber step into the center of the room.

“My dear subjects, I want to congratulate you all on how far you’ve been coming in such a short time. You are all changing in such wonderful ways and progressing nicely. With that in mind we have a special day before us.”

The subjects lining the rows were watching him intently. Nothing he was saying was very reassuring. In fact, it was terrifying, as every time Gruber said the word special it seemed to mean some sort of new change or agony.

Gruber continued, “You may have wondered what the strange light emanating box is in the center of the row. Well you are about to find out as we have two potential graduates today who will demonstrate their changes to you. Their readings to date have shown they have achieved the desired changes we seek. However, those changes have been calculated with their machines. We require real world demonstrations in the manner they will experience in the future. If they pass they will graduate from the room and head to newer and better things. If they fail, it is back to the machines for more manipulation and change.”

As he spoke a pair of nurses were leading two people to the light box in the center of the room. One male and one female, both looked worried and charged to complete their challenge and graduate.

“Here we have Yuki and Fritz,” Gruber said.

Leading Yuki to the box two nurses arranged her up on her knees, legs spread slightly facing toward the male row. A beautiful Asian girl, she was also quite dainty, no more than 5 feet tall and less than 100 pounds. Her wavy black hair swung past her shoulders and her sleek body glimmered from the lights emanating from below.

“Yuki has been through 200 sessions. To the eye she looks the same as the day she arrived, however with luck we will all see the success we have had with her internally.”

The nurses pulled her down and replaced Fritz in the same manner but facing toward the girl’s row. Beth gasped at seeing him – he cock was huge and it wasn’t even hard. Clear precum was dripping from the tip and his balls were easily the size of lemons. As she ogled the nurses began stroking his member, hardening it quickly. With each stroke it grew until it’s full length, easily 10 inches long and 5 inches thick, stood at throbbing attention. Then they pulled him down to standing position and pulled Yuki back up on the box. They arranged her on all fours facing the women and led Fritz behind her.

“Now we will begin your evaluation. You will fuck in the positions we indicate and you will not stop until I say. Enjoy your test!” Gruber and the nurses stepped away as the two subjects waited with anticipation. Yuki was already wet, her juices dripping onto the table below her. Fritz’s cock glistened with precum.

As the two waited the rows of machines holding the watching subjects hummed to life. Within moments they began their usual straining, orgasms, and manipulation. This time however they were watching Yuki and Fritz.

“Vaginal intercourse Fritz,” said Gruber.

Leaning forward Fritz began trying to penetrate Yuki. While her wetness should have made it simple his size was causing some frustration. Gripping her hips firmly he pulled her hard back against him and pushed his throbbing head past the tight resistance. Yuki let out a painful cry then whimpered as he began burrowing in deeper. When he felt her jerk as he bottomed out he pulled back then began a steady rhythm.

Pain quickly turned to pleasure as Yuki began thrusting back against him. Within moments she jerked and cried with a powerful orgasm. She would have collapsed had Fritz’s tight grip not held her hips up so he could continue his thrusting. A few thrusts later her head flew back again and she screamed as she came a second time.

This continued for a short while until Fritz began to pick up speed and grunt. Overcome with the intensity of the situation he had lost sense of Yuki’s pleasure and pain and slammed forward with all his might. Yuki screamed out in pain as his cock head crashed against her cervix then he released. For all watching his orgasm seemed to continue for an eternity. Within seconds white froth was pulsing out the sides of her vagina and splashing on the table below. Seeing this one of the new girls on a nearby machine became ill.

As his marathon cum began to subside Gruber stepped to the sweating, quivering couple. “Good, now to test the machine’s changes on Yuki. You see everyone, we hadn’t even manipulated her genitals during her sessions, and poor Yuki here knows what this evaluation is about for her. She has had dread in her eyes since she was led to the table, but I promise she will find it immensely pleasurable.”

Gruber stepped away then shouted over the sounds of the room, “Fritz, anal now.”

Yuki steadied and braced herself as Fritz’s still erect and turgid member brushed against her sphincter. There was no need for lube, the amount of ejaculate dripping from his hard cock was enough to wet the entrance.

With pressure his cock began sinking into her hole. Unlike her vagina that had provided some resistance her ass opened itself up. In fact, it seemed to Fritz as though it was trying to swallow his cock whole. Each inch sinking in deeper elicited new cries from Yuki. Despite his size and vigor they weren’t cries of agony. Rather, Yuki was clearly cumming from her ass – hard and repeatedly. Once all ten inches were buried fully inside she looked back over her shoulder and with a stern face said something in her native Japanese.

Gruber gleefully spoke up, “My dear Fritz, she says hard and fast.”

With that Yuki lurched forward then slammed back against Fritz, expelling and swallowing his entire member inside her ass in one quick movement. He grabbed her hips and together they entered a rapid trance like pace of slamming his huge member inside her ass. She came, over and over – harder each time. Shortly Fritz came again and Yuki cried out in ecstasy feeling his spunk splash throughout her.

Then she flipped over on her back, pulling Fritz into missionary. He continued pummeling her ass, cum splashing out with each thrust and the table glistening with sweat. He was again nearing his climax when it happened. Yuki screamed out in obvious pain rather than pleasure. Gruber came dashing up to watch more closely, he was obviously concerned.

Grabbing Fritz’s ass Gruber directed harder thrusting and watched as Yuki began writhing, struggling, and screaming in pain. He allowed Fritz to finish inside her again then directed him to slowly pull out. His cock head, swollen and an angry purple color, pulled out of her anus with some effort resulting in a popping sound. The nurses pulled her shaking form into a sitting position resulting in steady cum flowing from her ass and coating her thighs and the table in a pool nearly an inch deep.

Sitting in Fritz’s cum, shaking, and gently crying Yuki anticipated what was going to happen even before Gruber spoke. “Yuki, you have failed the evaluation. Since your recruitment in Kyoto we have been grooming you and testing you to become our anal success story. Your anus has been manipulated and filled with more pleasure nerves than any other part of your body, it has been stretched and made self-lubricating. The response to pain instead of pleasure then is problematic. We must continue your experiments.”

Gruber waved for the nurses who grabbed the sobbing Yuki be the arms and legs and began carrying her back to her machine in the row of women. Her screams and cries for another chance were ignored and soon the hum of her machine added to the sounds of the room.

Gruber turned to Fritz and smiled. “You have passed my dear man. Your volume is satisfactory and your lack of a refraction period is a resounding success! Please follow the nurses to your room.”

With that Fritz disappeared out the doors at the end of the corridor and Gruber turned again to the rows of experimentees. “My dear subjects, you have just witnessed the culmination of your experiments. While you are all being changed in various ways in the end you will either succeed like Fritz or suffer poor Yuki’s fate. Remember, it is not her fault, rather the experiment has not fine-tuned her biology yet. Soon enough she will be given another opportunity and when she succeeds can rest confident in the joy of her newly transformed self.”