When they reached the room, Essandra asked Kendra to wait there and went downstairs, returning shortly after with a chair. In the short time she waited, Kendra realized that Essandra's bed was too big for a normal girl, and it was also made of strong wood and had a very sturdy frame, which she believed would be able to comfortably support her weight in her centaur form.
"I'm glad I found someone else who volunteered for the trials, I wish I had someone I could open up to about this." Essandra said when they sit together at the desk
"Did you already know about me?" Kendra asked
"Not exactly. I knew there were other volunteers as it was obvious to me that they would not be content with just me. After I had made friends with the scientists they told me about the experiments they were doing. I learned that there were actually several experiments being carried out that were part of the same project, to prove that mythical creatures really existed and that their genes are dormant in people. They told me a lot, but they never told me how many volunteers they had in total or who they were, as that information was completely confidential. So I knew there was someone out there with the centaur gene, but I didn't know it was you." Essandra said
"Now that you say I remember hearing them mention that I was subject 133, that must mean there must be at least 132 besides me." Kendra said
"Or 150 beside the two of us, as I was subject 152." Essandra said
"You said before that you couldn't become a centaur because your DNA wasn't compatible. You were also part of the experiment so you should be able to transform into a creature too, am I right?" Kendra said
"Yes I can. My DNA wasn't compatible with centaurs, but it was with another creature." Essandra said
"So let me see into your 'true form'." Kendra said
"I personally don't have a problem with that, especially after I saw you in your centaur form." Saindra said, then got up and took off all her clothes informing Kendra that her true form was big and she didn't want to ruin her clothes.
Essandra's transformation was faster than Kendra expected. Kendra watched the girl grow and gain muscle, a tail growing behind her as her feet became hooves, however different from hers as a centaur. Her body was covered in black fur that had a few white dots while her head became entirely bovine, including a pair of large horns that grew from it. The most unexpected part of the transformation for Kendra was when Essandra's breasts shrank into a pectoral shape and her vagina inverted into a ballsack while her clit grew into a bovine penis.
"As you can see I am a minotaur. I understand your surprise, I was also surprised when I transformed for the first time, but in this form I am fully male. I never thought about the possibility of changing my gender before. The scientists said that I was not the only one and that instances of the 'true form' sex being different from that of the human form were not rare enough for me to be called an exception." Essandra said in her now fully male voice
"If that's how I should treat you now? I think I should treat you like a man, don't you think?" Kendra asked
"I'd rather you keep treating me like a girl. I may be an anthro bull now but inside I'm still the same girl and I prefer to be treated as such." Essandra said, returning to her human girl form shortly thereafter.
Kendra and Essandra continued talking for a while longer and with that Kendra learned that if she had continued with the tests she would have received the serum that allowed her to transform at will between forms, and that this new formula would not let the transformation be uncomfortable and not painful. She was also told that this serum was not definitive either, as they were researching a more advanced version that would have a permanent effect after a few sessions at most.
Eventually Essandra confessed that when Kendra arrived in the school locker room earlier, she wasn't just washing up, but had been jerking off in her minotaur form and had just come when she heard Kendra's entrance.
With that Kendra remembered that the colage must have been very horny and offered to fulfill her end of the bargain, concentrating and assuming her centaur form, offering her equine pussy to the girl. Quickly, Essandra accepted and started to eat Kendra's equine pussy, delighting in it until the half horse girl came.
Kendra likes the sensation, since it was the first time she had come in centaur form, as she couldn't reach her own genitals alone in this form and never asked anyone to. She then thought about what it would be like if a real dick was used, where would she get a boyfriend with a dick big enough for her centaur form? Then, remembering the minotaur version of Essandra, she asked the girl to fuck her.
"Can I really? You're not kidding, are you?" Essandra asked
"Yes you can. I want to feel you filling me." Kendra said
Essandra then changed into her minotaur form, with her cock already hard, and fucked Kendra (her height in this form being perfect for fucking the centaur.), saying "This feeling is so good. Thank you so much, I really wanted to do this. What's the use of being a man in my supernatural form if I'm too big for a normal woman. I was starting to think I'd have to look for a cow to fuck." She continued fucking Kendra and, when she felt that she was close to coming, she took her cock out of the centaur's pussy and stroked for a few seconds before she came, letting her bovine cum stick to the fur on Kendra's ass and tail.
After sex, the two girls took a shower and lay down on Essandra's bed, both staying in their supernatural forms, and slept a little. The bed was strong enough to bear the weight of the two of them together, even though in this form they weighed a ton and a half together.