It turned out there was a big flaw in Dixie's plan. Once Ty was injected into the horse, he regained control of his body. His sperm form swam into the waiting horse's egg and fertilized it. And as it did, Ty wished it would turn into a human egg. He started to re-develop, and wished he would grow until he'd be born and then continue to grow back to his regular age.
Inside the horse's womb, Ty grew and developed into a human foetus, and 9 minutes after he wished that, the horse birthed him. Moments later, his body started to age and develop. He grew to a young boy and then a teen, and soon Ty was back to his old self, standing naked next to a horse in a barn at Brookfield Farms. He appreciatively stroked the horse's mane as he waited for Dixie to get there.
Once she did, she saw Ty in front of her, and her jaw dropped. How had he managed to get back to human form after all she'd done to him? That slimy little... hot stud. Oh shit. Ty had used his wishing power to make them both go into heat. She had to admit, seeing his naked developed form like this was pretty fucking hot. And, even if he didn't have a horse's cock by any standard, his prick was still pretty big for a human, especially his age...
Ty smirked evilly, both their reservations fading as they kissed. He tore her halter top from her, unzipped her sundress, and pushed her to the floor of the barn. "Looks like you finally managed to get revenge," she said, her spite held back by her horniness.
After pulling her panties off and sucking on one of her boobs, making her moan, Ty looked up at her and smirked, "Oh, my revenge is just getting started." His cock head rubbed between Dixie's lips and along her clit, and she physically shook from the sensation. When his shaft pushed inside her, both their bodies felt so good they could burst. At this point, Dixie's body could only focus on the pleasure it felt, and as Ty pounded her, she clung to him instinctively.
"What are you -MMH- gonna do once you finish?" she breathed. "Cum in me? Hhahh~ B-breed me?"
"You c-could say that," Ty panted, thrusting faster and faster. Feeling Dixie's pussy cling to him and getting extremely close now, Ty made his wish. He and Dixie both started to shrink as they reached their orgasms, their bodies clinging to each other.
"Wha-" Dixie started, and then Ty kissed her and their lips and faces seemed to merge. Both their arms seemed to vanish, and their legs pressed together, merging into a tail which only formed part of Ty. Dixie suddenly realized what was happening as they both shrank more and more.
Soon, Dixie's body had regressed to a tiny sphere, and Ty's to an even smaller sphere with a long tail behind it. Dixie felt Ty's body wean itself into her own, and a weird twinge of pleasure rippled through her. Ty... Ty had just fertilized her. They were one person now!