Princess ate from her trough as she considered the recent events. She had gone from being a normal man to a mare, watched her friends and family undergo the same fate, and was now seemingly being forced to resign herself to her fate. Well, there were some perks to her new form she thought to herself as she looked at Harry in the adjacent stall.
Princess couldn't help but admire the stallion. Harry was the zoo's best stallion and exuded masculinity and strength. As Princess continued admiring the stallion, she felt a warmth in her nether region. Before long, the mare was leaking pungent juice from her pussy. Having not had recent access to the zoo's stallions, Princess' hormones begged for Harry and release. Unfortunately, it did not seem this release would come soon, as the zoo attendants had rushed off in a big hurry, leaving her locked in her stall.
A noise at the other end of the stable distracted Princess. She watched as a boy and girl ran towards her stall. Something about the children sparked a memory from her time as a human. "Isn't that Michael and Vivian? And what is that they're carrying?" Princess thought to herself. A shout from Vivian startled Princess from her thoughts as the human girl tripped and fell. One of the vials she was carrying flew from her arms, spaying into the horse water supply. The two children could only watch as the vial's contents took effect.
Curious about the new addition to their water, Harry and Princess stalked forward and took a sip of the liquid. The stallion and mare drank normally for a few seconds before the first visible changes occurred. Princess noticed the intense heat that had been circulating in her nether regions return in force as her lust spiked. She wasn't the only one feeling the change.
Princess' eyes were drawn to Harry and his rapidly hardening member. The stallion was breathing heavily, fully under the control of his hormones. His eyes focused on the pooling juices near Princess' hooves and her flowing pussy. This sight proved too much for the stallion. Harry reared and, with a loud whinny, ejaculated from his throbbing member. A torrent of cum proceeded to erupt from Harry's member all over his stall. The stallion was in a state of absolute ecstasy as he plunged his cock at anything that seemed capable of providing relief for his lust.
The display from Harry served to push Princess over the edge as well. The mare squirmed, whinnying herself, as streams of pussy juice sprayed from her nether region. She moved to grind against a nearby post, trying desperately to quench the heat. Instead, the heat intensified, causing more sprays of liquid and juices. Princess locked eyes with Harry across the aisle. He was in a similar state, expelling ejaculate at a frightening rate as he sought any avenue possible for release. It was then that she noted the next step of the change.
Harry began to shudder visibly, as his ejaculations and erection increased in intensity. Princess watched as the stallion's hooves became to form into fingers and then hands. The stallion's face began pulling back, becoming more humanoid in appearance. As this was happening, Harry began to decrease in size drastically, penis and balls standing out more clearly in the process. Princess eyed the massive appendage before she was forced to submit to her own changes.
The mare began shuddering herself as a long stream of liquid sprayed from her pussy over the surrounding stall. The mare's face became masculine in appearance, as did the rest of her body. Princess began to decrease in size, as she began to revert to her prior male form. Hooves became hands and horse teats shrunk to become a normal male chest. A particularly loud orgasm and moan signaled that Princess had regained her former speaking ability. The mare now groaned and moaned in deepening octaves as she/he continued to spray juices relentlessly. Princess glanced back towards Harry and was startled at what she saw.
By now, the stallion's body had diminished in size drastically. As Harry continued to thrust and hump, Princess saw two bumps begin to form on his diminishing masculine chest. The bumps formed into small pert mounds resembling the breasts of a human female. The rest of Harry's body followed suit, changing until it resembled that of a human woman. The previously undistinguishable humanoid head solidified in shape as the stallion's jet-black mane fell in hair like fashion behind it. Before long, the stallion had reverted into a middle-aged asian woman.
Partially regaining his old form did not detract from Harry's lust, but instead seemed to stoke it. As the asian woman was forced onto two feet, it was clear that she still had Harry's male equipment and instincts. The woman's penis was more erect than Harry's had ever been and her balls clearly full of horse seed. The asian woman/stallion hybrid moaned loudly and began thrusting at the stallion wall with greater intensity. Cum erupted from the equine shaft, spraying the surrounding walls and floor. Deep masculine groans became feminine grunts as the woman grasped her member with both hands and began rubbing it relentlessly. With a loud roar, Harry ejaculated again, falling to the floor of the stall from the force of the orgasm. All turned quiet as the woman caught her breath and her erection softened. The silence was broken by a sniffing sound from the woman.
The woman's head swung up, staring directly at Princess. The petite asian woman's flaccid cock rocketed upwards again, becoming fully erect. With a low growl, the woman ran and jumped into the former mare's stall. Princess stared with fear at the woman, clearly under the control of her male testosterone. With a low growl, the woman threw herself at Princess' behind. After several frantic jabs, the woman found the former mare's dwindling pussy and begun thrusting madly into it. Growls turned to moans as the woman mounted Princess in her last acts as a stallion, heavy balls aching for release. With one hard last thrust, the asian woman collapsed onto Princess as her cock and balls spasmed, emptying their contents.
The two former horses lay together for a time as their final changes progressed. The woman's penis retreated from Princess and into her body. At the same time, a cock and balls dropped from Princess's pussy, forcing the former stallion's cum out in the process. The asian woman got unsteadily to her feet, clarity returning to her as her balls pulled up into her now female pussy. The former horses looked at each other in embarrassment before the asian woman broke the silence.
"So, um, I'm Harriet." the woman said awkwardly.
Michael and Vivian watched at the stall door in stunning disbelief.