Carlos helped Chrissie to her feet after her urinal duties were finished.  He said, “There is one last thing that has been requested, but even with your particular vow of total control, you must agree to it of your own free will.  As you are still almost certainly affected by the interrogation serum, we can trust your answers to be honest.  Even with honest answers, you need to carefully consider what is about to be offered.  Come with me now.”

Carlos and Chrissie met with Candy outside of a green door in a darker hallway.  Carlos checked to see if the door was locked and found it open.  They entered and he turned on the dim lights, then locked the door behind them.  “You can leave at any time, but we do not want to be interrupted.  Both of you need to take a seat.  I have a short video for you two to watch.”

The video was a promotional video from Fartrotter Genetics about a gene therapy recently approved for trials in a number of species.  One of them happened to be rabbits.  It explained how it worked by altering the genes that maintained someone's sex.  Women’s ovaries could be made to produce testosterone and a man’s testicles could produce estrogen and progesterone.  All of the secondary sexual characteristics would change, but the actual reproductive and urinary tract would not be reformed.  A woman to man would still have a vagina, and a man to woman would still have a penis and testicles, just estrogen producing testicles.

After the video was over, Carlos brightened the lights to full and sat down opposite Candy and Chrissie.  He said, “This would be a much faster treatment than years of estrogen therapy.  If rabbits react like the mice that have so far done it, Chris could be Chrissie in body as well as heart in three months.”

“Three months?  How can a body change that fast?  What’s the catch?”Candy asked.

“There are several ‘catches’ as you say.  First, while the procedure is completely reversible in mice, that has not yet been tested in bunnies.  Second, it will cause infertility which may or may not be reversible.  Third, it does cause uncontrollable lactation in male to female mice for the first six or seven months after the initial change is complete and the breasts have grown in.  Female to male mice lose control of their bladders for some as yet unknown reason.  Fourth, I must reiterate that we still don’t know what all it will do in bunnies.”

“Wait, does Blake want me to do this too?”Candy asked, her imagination running wild.

“No, only Chrissie.  Mister Fartrotter said he likes your boobs as they are and doesn’t want you to become a c-boy, as some call it.”

Chrissie sighed wistfully, “I could be a real girl in 3 months…”

Carlos and Candy snapped back in unison, “You are a real girl!”

Candy added, “Genitals don’t make gender.”

“Quite right,”Carlos agreed.

Chrissie had a dreamy expression, “But I could have tits and no more male hormones.”

“Yes, if it works on bunnies.  Mister Fartrotter said he has some inside knowledge of one illegal bunny trial and said the results were unbelievable.  Unfortunately the bunny was sequestered by the R&D team until after bunny trials were approved, so he hasn’t gotten to learn anymore.”

Candy looked nervous.  “This sounds too risky.  I’m against it.”

Carlos nodded.  “That is quite understandable.  Let us proceed to move on to…”

Chrissie whispered, “I want it.”

Candy exclaimed, “Chrissie, are you out of your fucking mind?  You’ve only been a girl for 2 days.  I know you think you want this, but this is major life changing stuff and we don’t even know how our species will react to it.”

“Am I still speaking as me, not as your pet or slave?”

Candy nodded and Carlos reasserted that Chrissie was not to answer as a submissive.

“Then, my dear, loving sister, looking back at my life, I’ve been a girl since before puberty.  I just couldn’t admit that to myself until today.  This really isn’t as new as it seems.”

Candy hugged Chrissie.  “Yeah, I guess you have.  I didn’t want to admit it had been that long until now.  I have enjoyed so many fantasies of twincest and riding you in your sleep, but it never felt right so I never did it.  With you as a girl, I am going to be much more comfortable having incestuous fantasies and playing them out.”

Carlos’ voice once again grew more authoritative as he officially asked, “Chrissie Goldwater, are you absolutely sure that you wish to engage in this experimental gene therapy trial of your own free will?”

Chrissie nodded and replied, “I am.”

“Candice Goldwater, as one of the legal guardians of Chrissie as a submissive, you must also be in agreement with Chrissie and Mister Fartrotter for this to proceed.  Therefore, this gives you the power to blackball the experimental treatment.  Mister Fartrotter instructed us to assure you that he will be perfectly understanding if either of you have any misgivings about it and do not wish for Chrissie to go through with it.”

Candy hesitated then nodded.  “I accept the risk my sister wishes to take.”

“It is recorded that all three parties involved have agreed to the experimental gene therapy.  All that is needed now are the four injections.  Both of you please follow me to the medical wing.”

Moments later, Chrissie once again found herself strapped to a table and totally unable to move.  This time she was spread eagle, her only dignity being her chastity device and butt plug harness.  She didn’t mind.  She had enjoyed parading around nude the entire day with a store full of other nude or nearly nude people.  She wished the outside world could be more like this.

The injections were prepared.  A glowing purple liquid was injected directly into Chrissie’s right nipple.  She yelped at the pain.  The entire right side of her chest suddenly felt frozen.  The second injection was into her left nipple.  It hurt even worse and had the same frozen sensation.  Because of the way she was strapped in, Chrissie had an idea where the next two shots were going to go and she didn’t like it.

When the third injection went into her right testicle, she was surprised that it wasn’t as painful as her nipple had been.  She also didn’t experience the freezing sensation.  The final injection into her left testicle hurt enough to make her yelp, but then it was over.  A moment later it felt like someone was forcing her testicles into boiling water.

The nurse who gave the injections recorded everything that Chrissie had told her about the experience.  She was then released from the table and given a pamphlet on things to watch out for.  The nurse then added, “For the mice that got cold in the chest and hot in the balls like you did, the transition happened much faster.  Your breasts may even be noticeable in about a week.  Those who reported frozen balls and a burning chest took twice as long.  Again, that was mice, not bunnies.  Also, do not ejaculate for two hours after the shots.”

Candy assured her that wouldn’t be a problem, causing Chrissie to blush.  A quick text message from Candy to Blake and the buttplug in Chrissie’s ass stopped vibrating, which caused Chrissie to whimper.  The huge rubber phallus was much easier to enjoy when it was making her prostate drool.

From the medical area they went to the front of the store.  Carlos handed the cashier the items that Chrissie wasn’t wearing, plus a note containing the ones she was wearing.  Chrissie almost fainted when she saw the total come to well over $5,000.

Candy too was shocked.  “Oh. My. Goddess.  The chastity shields were $1500 each.  No, yours was $1600.” She quickly texted Blake, in a panic.

His reply was a smiley face, a thumbs up, and a kissy face.

“I hate emoji answers,”Candy muttered, wiping a tear from her eye.  She turned to her twin and showed Chrissie the response text.  Chrissie didn’t know what to say, letting her mouth hang open.

Carlos said, “By request of Mister Fartrotter, all purchases not currently worn will be delivered by private courier once you signal me that you are safely home.  I would recommend that the two of you leave kink town within the hour, before the afternoon parties start.  We wouldn’t want to see either of you little doe bunnies roofied and stolen away for a sex party.  Mister Fartrotter has said that if we do not hear from you in three hours to alert the authorities.  Your chastity devices both have trackers in them and are quite impossible to remove without the assistance of emergency personnel.”

Candy nodded and handed Chrissie her meager clothes while she put her own back on.  Carlos handed her Chrissie’s leash and bowed professionally.  “We look forward to your next visit.”

A little to Candy’s disappointment but much to Chrissie’s relief the bus ride home was uneventful.  They got off the bus five blocks earlier than they needed to, just to avoid any last minute passengers from their immediate neighborhood.  Both of them had also left a significant wet spot from their individual sexual juices on the bus seats.  The next week was going to be a challenge keeping their clothes dry with the constant arousal.

Half an hour later their purchases were delivered by a suit-wearing, but very squirmy individual.  They guessed that the person was being sexually stimulated under their clothes, where no one would be able to notice.  At least not if the delivery person could stand straight.

Up in Candy’s bedroom, Candy got a text from Blake giving her partial access to her chastity shield so she could close and open the drain holes when she wanted.  He also told her that there was a hose she could attach to it that she could have Chrissie drink from or put it in Chrissie’s penis gag if Chrissie was being reluctant.  It would ensure that there was no risk of spillage and no need to attach the urinal bowl and penis gag.  He also texted her about a one-way valve hose that was to be attached between Chrissie’s drain hole and her buttplug.  He said he wanted Chrissie wearing that at all times she was wearing the buttplug.

Candy was worried that it wasn’t healthy but Blake assured her that he would increase Chrissie’s unlock frequency so that she could drain her ass of pee and precum when they got home from school, before bed, and first thing in the morning.  He closed by saying he wished he could come over but once he was done working at his dad’s place, he had to get on a conference call with his grandmother about his annual 1-week of hell at the stud farm.  He was happy that he at least didn’t have to perform any breeding duties there yet.

Chrissie looked at her sister.  “Candy, what do I do for my last week of school?  I can’t suddenly be Chrissie.  I’ll get pounded into the ground even with Blake protecting me, maybe even expelled for cross-dressing without giving the school 90 days advance notice before coming out as trans.”

“Well, Sister, you will pretend to be Chris for one more week.  You’ve been pretending to be a guy for, what, 6 years now?  Even if your breasts start coming in they will still be small enough that they can easily be hidden by an extra t-shirt.”

“Dad’s gonna freak like he did when Caitlin came out.”

“Yeah, and mom will ‘talk’ some sense into him.  We’ll wait until we’re on our post graduation trip with Blake before we tell Dad, but I want Mom to know as soon as they get home and we can talk to her in private.”

Chrissie nodded to her sister and gave her a loving kiss.  Candy turned it into a passionate one, causing Chrissie to once again strain against her chastity cone.  The arousal without being able to touch herself made it feel even better, despite how frustrating it was not to be able to cum whenever she wanted.