What was that injection?

When Jessica suggested the proposal to Debbie she told her that if they were to proceed with the arrangement that she'd need to submit a blood sample for a blood test and that if that was fine they'd inject her with a super strength contraceptive to ensure that she didn't end up accidently or purposefully with child. Debbie was agreeable to this as three kids was enough given their current budget and she didn't want to try explaining away a child that didn't come from her husbands balls to him. The sample really was a drawing of blood and it was tested for STD's and other medical issues that might be present... but there was another reason for the sample.

Years earlier John invested in a startup genetic sequencing company that had been working on a similar thing to CRISPR, basically rewriting DNA to do certain things. Initially they'd been wanting to develop a way to write diseases out of the genes and prevent diseases like cancer etc, but after years of work on this they were struggling to eliminate all the types of diseases without harming the hosts or causing unwanted side effects.

Apparently evolution gives diseases along with benefits and if you make disease impossible the genes breakdown, a kind of universal balancing mechanism. They did however in the process of their mapping the genome learn how certain body parts are coded into the body, such as eye colour, hair colour, number of fingers and much more. This then spurred on a series of developments for the business from its original goals of eradicating all disease to non-invasive cosmetic surgery, no need to go under the knife to have bigger titties or a bigger cock when changing a couple of values in your DNA tells your body to naturally do the changes. There were a number of software engineers brought in, who with the expertise of the geneticists were able to make a very simple user friendly device to do the changes you desire and you could even make specific genetic subroutines just like if you were coding a program into an arduino. The prototype device simply requires a sample of DNA and then after it scans the DNA it shows a graphical interface of the human body, clicking on the different parts opens a display with the currently configured attributes and the options that can be altered, it can then simulate what the effect would be to the person. In order to figure out how values like penis length are coded involved the use of a supercomputer and tens of thousands of DNA Samples matched with physical information obtained through a paid survey, this was relatively easy as almost anyone is willing to have a blood sample taken and a 2 hour physical when they get paid 5k after.

The technology would not be publicly available for at least another ten years but as the owner of the company he got shown the technology demonstrated on rats and after seeing a dozen rats live out their lifespans in bright green fur or looking like a 6" T-rex he realised the technology was viable. Due to how hazardous such a technology would be in the wrong hands the device requires multiple security keys to activate it for use, otherwise its effectively just a very expensive lamp.

After a few years of them doing tests on various animals to no negative effects he knew that he wanted to make changes to himself, the scientists wouldn't do it though as it would be illegal without government approval of the device, but he had the software engineers add in a login for him on the machine and with his access out of hours to the building he could do what he wanted when no-one was about.

When you make the finalise your intended changes the machine makes some noises and then after about an hour it produces a vial of liquid that when injected causes the body to start making the changes, this process takes about an hour in a rat, but in a human would likely take 6-8 hours for the changes to propagate. As John was doing this illegally and out of hours he couldn't exactly ask for help if he was unsure about anything so he figured he best test out his work on something else before himself. So he made his proposed changes on some rats and checked they were ok for several months after his changes to them. When he was confident they worked he made his body have a higher metabolism so he'd get in shape faster and naturally altered his cock and balls. Increasing both their length, girth, capacity, and even altering the flavour and virility of his cum. He was very pleased with the results as were his female partners whom always seemed to enjoy their intimate time with his enhanced body.

Now for the sample he got from Debbie...

First step was to run it through the sequencer to both check for and eliminate any STD's then it presented a virtual model of her body as it is, John clicked a button and it showed her internal organs, he clicked her ovaries and found he could stop them producing eggs (effectively sterilising her) but he could alternatively alter the structure of her eggs making them have a harder shell than sperm could penetrate by simply adding a mineral coating to them, if pregnancy was desired then the sperm donor would simply need to consume a pill with concentrated minerals in advance and his sperm would then have the required strength to fertilise her egg. The changes to Debbie would be permanent and given that this technology was a secret, he would be the only way she could ever get pregnant in the future.

He had seen her lingerie pictures and been provided her measurements by Jessica and decided he'd like to see her with slightly bigger breasts, not massive but a cup size or two bigger, he also increased her sexual desire and added in a slight change to her biochemistry so she couldn't absorb a certain mineral from food... the same mineral that made his sperm have a different flavour.

He had given a similar alteration to Jessica but made her breasts a lot bigger and her sex drive and pheromones much more prolific... at her suggestion. She went up 5 cup sizes and needed a cock in her at least twice a day or she would get the shakes like an junkie needing a fix, her happiness in general and enjoyment of life did improve significantly afterwards though so she considered it a win-win. She was unaware of the way the contraception worked but knew it was successful as she'd been taking a lot of cream pies over the years since it was done and never got pregnant. The process took a few days to execute in Jessica hence why they had to dose Debbie well in advance of the start of the deal.

Now back to the present day...