The young man indicated was already admiring Derrick as he approached. "A nice start. I take it you like horses?" Derrick nodded. "I spent a long time as a mare, but I needed to get back before my family came back from thier tour." Poseidon nodded. "Centaurs are OK, but too much human. I prefer the pure breed. A beautiful drafter stallion or mare." He looked to be in his early twenties, with shoulder-length blonde hair and very green eyes.
Derrick grinned. "You sound like Hephaustus. And I guess that wouldn't be bad at all, but I'd want to go slow. No point in spending the whole vacation as an animal." Poseidon chuckled. "That depends. If a stallion had enough mares, he could easily enjoy the whole two weeks mounting." Just the mention of mares got Derrick's equine-like cock aroused, and the boy hefted his swelling penis. "Yeah, problem would be finding that many willing mares." Poseidon waggled his eyebrows. "Not a problem at all with the right help." He reached out and stroked the tip of Derrick's already erect penis and the boy gasped as heat and pressure ran through the organ. It swelled out to an even more impressive size, coal black and dribbling semen.
But the transformation did not stop there - Derrick's legs got longer and changed shape with glossy black fur covered his skin, and feet swelling out and hardening into massive hooves. The boy gaped at what had to be the most perfect black Shire stallion's hindquarters to ever exist. Poseidon chuckled as the black hair swept up Derrick's growing upper body. "I promise you won't get bored. And your family won't miss you at all."
The receptionist walked over. "Now, Poseidon, you can't go turning every young man you see into a horse. There are so many other possibilities the kid can check out." The god grinned, still holding the end of Derrick's shaft. "I assure you that all the boy wants to do is mount mares. You know I wouldn't affect his mind. Tell her, my soon-to-be stallion."
It was hard to talk, only partly because his head was starting to become a horse's. Derrick felt the transformation, knew he was being turned into a horse, but his whole being seemed focused around the monster black cock and swollen testicles. "I... want... this." It took everything Derrick had to say those words, and as he did he fell forward onto huge hooves and solid forelegs as a black Shire stallion.
Poseidon let go of the swinging organ and ran his hands over the new animal's flanks and back, then stroked the massive neck and head. Derrick felt power from each touch, many little changes that the god made to perfect his form. When he was done, he stepped back to admire the huge black animal. "Some of my best work! And to make sure you don't waste all the semen those churning testicles produce?" He waved a hand and Derrick vanished,
"Was that a horse?" Derricks mother, father, and sister came walking up behind the god and receptionist. "My son would love that. He is into horses." The receptionist rolled her eyes and went back to her desk. Poseidon grinned. "Oh, I am sure he will be 'into' a lot of mares. He will sire a lot of foals for me before he gets the chance to be human again."
"Wait." Derrick's father frowned. "Was that Derrick? Derrick is going to spend the whole two weeks as a horse?" Poseidon cocked his head and looked curious. "Derrick? Who is Derrick? The horse that I just sent to my herd is a perfect Shire stallion named Sampson."
Derrick's father opened his mouth, then seemed puzzled. "What was I asking?" Derrick's mother shrugged. "I have no idea. Why don't we see if the Spa has rooms ready for us. We'll need two bedrooms, remember. One for us, and one for Julie." The family headed away, no longer aware there has been a son and brother. Maybe if Derrick got tired of being a stallion after two weeks, Poseidon would send him home with them. Maybe.