They had passed through the corridor to a fully equipped spa area. Tilda saw a small sauna and a swimming pool, fully equipped with a hoist and pulley system to make it accessible. And a small jacuzzi with an additional hoist. After Mark had explained how to use the hoist, he had disappeared to fetch her fresh towels. Knowing how much he would enjoy the show, Tilda had waited for Mark to return with her towels before she began the slow process of transferring herself onto the seat of the hoist. He watched in awe as she dragged herself onto the plastic seat, her limp legs dragging behind her. She pulled them closer and lifted her feet over the edge of the already bubbling pool. She was rewarded with the sight of another bulge forming in his trousers.

Tilda pressed the button, and the seat slowly lowered her into the water. She watched as her legs were submerged and finally, the water reached the line where her sensation began, and she sighed softly as the warm water hit her.

As the machine stopped, she slid off the seat to float in the pool.

Mark swallowed audibly. "If you need anything, there's an emergency button on the left. And the panel over here," he pointed to a touch screen, "controls the temperature and intensity of the airflow." Mark laid the towels on her wheelchair cushion. "And I think Patricia might join you in a moment. You have a similar effect on her as you do on me." He winked.

"Good to know." Tilda smiled. "Thank you."

"You're welcome, see you for dinner I guess." He waved, leaving her to her own devices.

Tilda turned and wiggled around in the small pool until she found one of the moulded seats and pulled herself in. She closed her eyes and enjoyed the soothing effect of the warm water.

She must have dozed off a little when the sound of someone entering the pool woke her up. She looked up to see Patricia's dark, naked body slowly submerge in front of her.

"I hope you don't mind if I join you?"

"Of course not!" Tilda smiled. She felt the familiar tingling return.

Patricia sat opposite her, Tilda's limp feet moving in the bubbling water between them.

The dark woman carefully held Tilda’s ankles to keep her feet and calves submerged. "May I?" She began to stroke and caress Tilda's lower legs and feet.

"You know I can't feel them?"

"Yes, but if you haven't guessed by now, I am a devotee like Mark. And it turns me on to play with your feet."

Tilda nodded slowly. "Okay, do you need to be turned on more?" She grinned.

Patricia blushed a little. "Not really."

She watched as her legs disappeared into the bubbling water, Patricia moved a little and smiled.

"May I use your foot to please myself? Watching you orgasm like that still makes me hot."

Tilda tilted her head. She had never done anything like that, and if she was honest with herself, she was still not doing anything, it was Patricia who was. But she was intrigued.

"Only if I can watch."

Patricia beamed. She turned around until she reached a control panel and turned the bubbles down to a very low simmer. The surface calmed down and Tilda could finally see what was going on under the water. Patricia turned her attention back to her feet, caressing and massaging them, she decided on her left foot and started pulling on her big toe, rubbing it as if she was giving it a hand job. Tilda watched in awe as she pulled the foot closer and spread her legs wider. She watched as Patricia circled her clit with her big toe. Her excitement was visible in her flushed face.

Tilda hadn't thought she could get excited again after that earth-shattering orgasm earlier. She realised that Patricia was watching her. She saw the pleasure on Tilda's face, and it turned her on even more.

Tilda looked into her eyes. "Is my foot fucking you well?"

Patricia bit her lip and nodded. Tilda watched as her toes disappeared between her folds. Patricia's hips began to buckle as she rode her limp foot. She had noticed her nipples getting hard and erect again, the warm water leaving a nice tingling sensation, her hands found the sensitive buds and she began to pull and roll them between her fingers.

As she watched, Patricia's moans grew louder, and she shivered as the orgasm hit her. Moaning and groaning, she ground against Tilda's foot.

Still catching her breath, she looked at Tilda and asked, "Did you enjoy the show?"

"Not as much as you enjoyed my foot." She grinned.

"Well, I think I enjoyed it quite a bit." Mark's voice came from the doorway. Grinning, he approached the women. Judging by his trousers, he must have watched them for a while.

"I came down to see if I should pick you up for dinner, but I stayed for the show." He grinned.

Tilda blushed a little. "Is it that late?"

Mark nodded.

"Oh dear, now that I think about it, I'm starving," Tilda admitted.

Patricia and Mark helped her out of the pool and towelled her dry.

"I wonder," Mark mused. "Would you be up for another round of testing after dinner? Tomorrow is Sunday and we'll only be able to continue testing until lunchtime."

Tilda smiled. She was already aroused again, something she hadn't thought possible so soon after this afternoon's events. But here she was, nodding happily in agreement.

"What's next?" Mark had her back in her wheelchair, her dress draped loosely over her body.

He wheeled her back to her room while Patricia tidied herself and the pool area. She would join them later.

"We have established that you can achieve an orgasm, now we will begin to build up how much technical assistance you will need. If you don't mind having a running vibrator inside you, I would like to use the time during dinner to try and increase your arousal and the chances of you getting wet on your own. After dinner, with your consent, of course, I would have intercourse with you. Unfortunately, I don't think I'll be able to bring you to orgasm the first time, but we can try a few things to stimulate you. Patricia has offered," he made air quotes, "to finish the job and give you another machine-induced orgasm later for your pleasure.

"Intercourse with you is more for your pleasure than mine, I suppose?" Tilda smiled.

"Well, I admit I am looking forward to it. You can of course choose another male partner, but we need some data that only a flesh-and-blood penis can collect inside you. Since intimacy also plays a role in achieving an orgasm."

Tilda nodded. They had reached her room, and she had opened the door for them. Once he'd wheeled her in, Tilda took over and began to push herself towards her bed. When she reached the bedside table, she turned. "Can I choose, or do you have a recommendation?"

Now it was Mark's turn to grin as he opened the bedside table and pulled out the vibrator, they had used on the machine earlier, the copy of his member.

"Who would have thought?" Tilda turned a few inches towards Mark. "We should get it wet before you put it in." She locked eyes with him and parted her lips slightly. He immediately understood what she had in mind and slowly pushed the vibrator towards her. She allowed the toy to part her lips even more before she enveloped it and began to give it head. From the corner of her eye, she could see Mark's erection struggling against the fabric of his trousers. He moaned softly as he watched her do to the toy what she had done to the real thing not so long before.

Leaning back, she let the toy slip from her mouth, a thin string of saliva connecting them.

"I suppose you want to put it inside me yourself?" She raised a curious eyebrow.

"If I may?" Mark's voice was full of lust. Still leaning back, Tilda grabbed her knees and tried to spread her legs further apart. Mark removed her dress and knelt in front of her. He spread her lips with his hand and carefully pushed the lifelike vibrator inside her. Once it was deep inside her he switched it on and got a pair of panties from another drawer to hold it in place. He helped her into the panties and Tilda decided that a bathrobe would do for a dinner dress.

She wheeled herself into the dining room, Mark walking beside her, the bulge in his trousers right in her line of sight. She was convinced she could hear the toy humming inside her, but sadly she could not feel it, although sometimes when she leaned forward for a push, she thought she could feel a little pressure.

They had a nice, relaxed dinner in the dining room. After dessert, Tilda noticed how restless Mark was becoming.

"Time for bed?" she asked in a hoarse voice.

Mark swallowed and nodded.