"It's true" the woman states matter of factly as she walks into the room and turns on a TV on the far wall.
The first thing I see is my sister walking through the zoo calling out for my parents. I strain against the restraints holding me back, knowing that I have to warn her of the fate that awaits her in this twisted place.
"Don't worry, you'll be reunited soon enough," the woman calmly says. "I just need to provide the right bait to bring everyone together". The woman pulls out a remote and switches the TV to a different camera feed.
The new feed is showing my mother and father in their corrals eating out of a trough. Both stallions appear appalled at their current state, but have no choice but to go along with the woman's plans. It was a couple minutes before I noticed a change.
All of a sudden, my father whinnied loudly and ejaculated streams of cum all over the floor. My nearby mother watched in horror as my father began to shake. I could hear the sound of cracking bones in addition to his whinnying. At the same time, the hormones produced by his stallion equipment continued to push into overdrive as the ejaculations continued and he began thrusting into the stall wall to relieve the growing pressure. That's when I noticed my mother start to change as well.
Similar to my father, my mother's mouth went wide as she spontaneously ejaculated hard into the wall of the stall. While the sounds of cracking bones began emanating from her body, she began to thrust desperately at the stall wall. Being previously female, she was not used to the large doses of testosterone streaming through her body. She began doing anything she could to relieve the growing pressure, thrusting with such force that the stall was shaking. It wasn't long before both my mother and father had cum numerous times into their stalls.
As I continued to watch, I noticed my father's testicles declining in size as they expelled more and more cum. It wasn't long before they were the size of human testicles. His penis also reduced in length and became that of a normal human. His face followed the same trend, with the horse muzzle retreating and his face returning to that before the transformation. The rest of his body followed and before long he was my father again. Just as I thought the transformation was finished, he let loose one last bellow and came hard all over the side of the stall.
At this stage the camera zoomed in on my mother. As with my father, my mother's balls were declining in size as they expelled their cum and there was less testosterone fueling her lust-driven mind. While she continued to thrust at the stall, her face began to return to normal and her body became more human in appearance. Two buds began growing in on her torso, as her breasts reformed and her feminine traits returned. Before long, I was watching my mother in her original form humping the stall furiously. Eventually, as the transformation finished, she roared as she climaxed all over her stall. After several long ejaculations, my mother's penis and balls retreated and she was left with her original vagina.
Both parents climbed out their stalls and embraced as they reunited. Both wore cheeks crimson with embarrassment as they realized what they had done. I continued to watch as my mother and father grabbed some clothes out of nearby lockers and ran from the stables.
The screen then switched back to my sister. I watched as my mother and father ran up to her and began hurriedly ushering her towards the exit. I watched hopefully as they neared the exit of the zoo.
"No, no, no, that won't do at all" intoned the woman. "Good thing your parents are unwittingly adding another beast to my herd. I recoiled in horror as I watched my now human parents hurry with my sister towards the next stage of the woman's plan.