As Beth lay helplessly over Ben's strong muscular thighs, he began to pull and twist on the butt plug again, gently thrusting it in and out of her bottom whilst she panted and writhed. Eventually, the plug popped out of her bottom and she began rhythmically clenching in reaction to the sudden emptiness.

Ben opened a drawer behind him and as the contents was almost level with her face, Beth saw an array of plugs. There were several rows for each design and all had their own compartment in the drawer. All were in graduated size order, shiny and silver.

Beth gasped as Ben selected one of the plugs. It wasn't the biggest, she was thankful for that but it was far from small! Surely he didn't think that was going to fit up her bottom???

Evidently, Ben thought it would, as seconds later, Beth felt a sudden squelch of cold gloop squirted into her tender hole followed by intense pressure and stretching as the cold hard plug slid slowly and firmly into her bottom, making her squeal in surprise and discomfort.

"Owww, Ben! Nooo, It's too big"

Immediately, her internal muscles began to pulsate in response to the alien invasion and another wave of intense arousal shot through her body.

"Just breath, through it and let your body relax and adjust. I will be training your bottom so that it's easy for you to accept and receive all kinds of pleasure"

Whilst Beth was distracted and concentrating on the size of the plug, Ben had prepared to give her the first of the two injections in her bottom. She barely registered him quickly swiping the area with surgical spirit.

"Ok Beth, Vitamin C injection is coming now. This is going to burn like mad, sorry but I need you to hold very still for me..."

Ben held her firmly in place, his large capable hand at the small of her back, pinning her down across his lap. He held the syringe like a dart and quickly and expertly drove the one and a half inch needle deeply into her upper outer cheek then slowly began to depress the plunger emptying all of the yellow liquid into her body.

Beth cried out in shock at the sudden sharp sting as it pierced her already tender scorched bottom and made its way deeply into her muscle but it was nothing in comparison to the burn of the serum. The pain was so bad she couldn't help it, she immediately began to cry as second by second, a thousand angry hornets were repeatedly biting into her flesh, leaving a burning ball of fire and a feeling as though there was a tennis ball inserted under her skin.

Whilst Ben took care of her, wiping away the tiny bead of blood with cotton wool and firmly pressing down on the injection site, Beth lay limply across his lap sobbing softly whilst he applied a plaster. Slowly the pain began to subside to just hot throbbing and she was able to move again. Gingerly she reached up to feel the tender area just below her hip. It felt hot and swollen. That had been the most painful of all the injections and he was still not finished. There was still one more to go.

"I don't want that last one!" Beth yelled indignantly when she saw him reach for the next syringe. She tried repeatedly to get up from across his lap. "I don't care how good for me it is, I'm not having any more, you can't make me!"

Ben was not in the slightest bit moved by her tantrum and instead gave her a quick volley of swots across her bottom and swiftly clamped her in position with his leg.

"Lay still Bethany! This is for your own good as you well know. Behave yourself or you will be getting a much harder spanking as well as the much needed injection."

His stern dressing down had the desired affect and begrudgingly, Beth lay still in quiet surrender. The final shot was Glutathione and she yelped loudly as it was driven into the muscle of her left cheek. Ben pushed the plunger down slowly and immediately the amino acid began to rip through her muscle causing a renewal of fresh tears. Beth balled her fist and thumped his calf in time to the throbbing burning pain that seemed to travel down her thigh. "

Despite the thumping, Ben was, as ever, cool calm and collected and stroked her back soothingly until the burning subsided.

"Well done Beth. All the nasty shots are done now and you will feel much better in no time. "

Beth sniffed and pouted. She felt exhausted, sore and embarrassed that she had behaved like a baby. Her bottom, thighs and arms were all throbbing. Ben scooped her up and lay her on the exam table face down.

"Right then. On to your hands and knees. Let's have a really good look at your bottom shall we and get some serious anal training under way?.... "

What would the anal training involve, Beth wondered?