Mark let out a whinny as he felt the mare lick at his shaft as he turned his head away from the fountain to look at Princess. His massive horse cock stood at attention as she continued to lick along the shaft towards his flared tip. The thought crossed his mind for a moment that it was wrong to have sex with this mare, but he pushed it away, she was a mare and he was a stallion, there was nothing else to do as he thrusted into the air before he came.
He let out a sad whinny as he felt the mare's tongue leave his shaft. He looked down at his reflection again, there was something wrong about it, like it was unfamiliar to him but the stallion couldn't place it. He heard an impatient neigh behind him and he turned to see Princess standing there with her back to him as she looked at him, her tail pushed to the side as her waiting vagina winked at him.
There was no more doubt's in the stallion's mind as he pushed his muzzle in close and licked at her vagina a little, the scent of her heat filling his nostrils as his cock stood at attention again. As his tongue probed at the folds of the mare and her juices flowed over his tongue, the last of his human mind slipped away, replaced only with a proud stud that was ready to take this mare as his own.
Princess smiled as she looked back at Mark and wiggled her flanks suggestively. She wanted this stallion inside her folds, she didn't care that she had just transformed a human into a stallion, she wanted to be mated!
Her wish was soon granted as she felt the stallion's weight against her as he mounted her. He thrust his cock deep into her and she let out a whinny as she felt the stud thrust faster and deeper into her. While this was the second time she had been mounted, she felt more excited, more in control this time as she felt the stallion pierce her folds.
She whinnied as she felt their wet fur rubbing against each other as Mark thrust faster and deeper into her. She neighed as the thrusts sent shivers up and down her spine, the still alien feeling of a cock penetrating her vagina felt amazing as she started to move her hindquarters with his thrusts, feeling his balls slapping against her as he thrust in as deep as he could.
Mark let out a neigh as he thrust into his mare one last time, where there was once an uneasy and inexperienced young man there was now a proud stallion that wanted to impregnate the mare, and she wanted the same. They whinnied in unison as his cum spurted out into the mare as her vaginal muscles clamped down and drew as much of the stallion's seed out as it could.
Mark breathed heavily as he pulled out of her, causing some of the mixed juices to pour down her hind legs. He started to eat the grass nearby as Princess stared at the fountain.
She was tempted to drink from the fountain herself. It may get rid of her human mind and thoughts and let her immerse herself in the horse body she now had. She still remembered everything of her human life, and it bugged her, maybe she should just give in and lose all of that.