After being taken to his stall, Parker can't help himself as he tries to get a better look at his new body. The bridle had made him into a powerful stallion, but he was having trouble seeing just how far it'd gone. His newfound confidence had allowed him to imagine himself more potent, more powerful, more endowed than he ever would've dared before and... and he found himself confident that he matched up. Thankfully he hadn't lost much of his human intellect, even if his mind was suffused with his strong stallion hormones. Standing in the stall, his mind turned towards his supposed newfound virility, feeling it was time to... well, put it to the test.
Parker let his mind flood with the images of mating he'd seen at the stables, stallions on top of their mares, plunging into them. He could feel his enormous shaft pushing out from his new sheath, hanging down beneath him. His enormous, potent balls, weighing heavy in his sack. His instincts helped him, pushing him to flex his shaft, slapping it against his belly over and over, feeling it flop down bigger and heavier with every repetition. Soon enough, he could feel his balls pull up, could feel his stallion seed rushing through him, his cock flaring even thicker as it went rigid against his belly, before his load sprayed out against one of the stall walls, painting it with his spunk. Jet after jet left him, and in that moment both his human and horse instincts converged, a single question burning through him.
"What if I was bigger? More Potent? More Virile? Why did I imagine myself with these limits..."
As his orgasm tapered off, that same thought pounded through his head, and an exhausted Parker felt himself growing drowzy, falling to sleep with that thought repeating in his head, the thought that he could imagine himself with even bigger balls, spewing even messier, more potent loads. As he slept though, his body recharged itself from his exhausting orgasm, and then kept improving itself, his testicles growing slightly larger, churning up an even bigger load.
Once he woke, Parker shifted before realizing that the weight between his legs had grown. Looking as best he could, he couldn't believe his eyes, couldn't understand how his balls had enlarged even more as he slept. Eventually though, the pieces clicked, and he realized what must have happened. He remembered the Doctor's order.
"Parker I want you to transform into the largest, strongest, best-endowed and most confident stallion that you can possibly imagine.”
Imagine... the bridle's command was still in effect! He had grown because he'd imagined himself even larger. With that new knowledge, coupled with his stallion's confidence and human cunning, he began to plan... wondering how else he could manipulate Liam and Doctor Jenkins' poorly worded order.