Jimmy's mind reeled, as he tried to understand what was happening to him. His upper body had become hard and strong, instantly. Everything he knew about physics, biology, chemistry... hell, the very laws of nature said it was impossible.
And of course, so it was. But Ty's power was supernatural, so the laws of science and nature didn't apply. But Jimmy didn't realize that yet, even as his mind raced to try and rationalize what was happening.
Ty grinned, watching Jimmy's confusion. Slowly, Jimmy's legs grew, thicker and harder, muscle slowly filling his narrow-legged pants. His ass became firm and round, a pair of mighty glutes, as his back thickened and swelled, his shoulder and traps mounding up. His shirt, a sensible polo, struggled to contain the new Jimmy, stretched tight over his swollen chest, his thick arms.
"This is... impossible..." Jimmy whispered, running his hand over his chest, feeling how thick and solid his pecs now were. "This is... incredible!" A huge grin came over Jimmy's face, and he lifted his arms, flexing his now quite impressive biceps, watching the round balls of hard muscle rise under the sleeves, straining them. "Oh fuck yeah!"
To the side, the invisible Ty and Dustin watched as Jimmy happily explored his new body. Still short, but no longer skinny, Jimmy looked like he could walk on to the wrestling team without any trouble. But Ty had grander ideas.
Jimmy's head snapped up, as Ty and Dustin suddenly appeared. "Where did you come from?" he gasped, looking away from his flexed arms.
"We've been here the whole time," Ty explained, "I'm tired of the geeks in this school being scrawny, and getting picked on. I decided to change things around a bit. I take it you like my project so far?"
Jimmy grinned widely. "Are you kidding? I love this!" He flexed his strong arms for emphasis, the defined, strong muscles jumping at his command.
"Want more?" Ty asked slyly, his voice seductive.
"Oh hell yeah!" Jimmy responded enthusiastically.
"Now, for phase two..." Ty chuckled, as Dustin stepped back, not sure what was going to happen.
Jimmy threw his head back and howled in pleasure, as a series of slow, rolling convulsions swept over his muscular body. Every vein stood up under his skin, pulsating powerfully. Then he began to swell, his muscles getting even bigger and stronger, swelling dramatically under his clothes. His pecs bloated outward, big hard slabs of beef, straining his shirt further. His arms grew thicker and harder, the biceps and triceps stretching his sleeves until they popped, the cloth and elastic stretching until they gave way.
"Oh yeah!" Jimmy groaned, pumping his arms enthusiastically, loving the sight of his big guns and the torn sleeves around them. His back and shoulders mounded up big and freaky, and the rest of his shirt began to tear, unable to contain his thickly muscled torso. First the buttons popped off, one by one, and then the shirt began to tear down the front, Jimmy's big pecs slowly revealed by the spreading fabric. With a grunt of triumph, he pulled the tattered shirt from his body, just as his huge legs burst through his pants, the big quads unwilling to be contained any longer. Jimmy groaned, and pulled his pants off as well.
The growth subsided, and Ty and Dustin stared at Jimmy. Standing in the center of the room, Jimmy was still at his old height. But he was the opposite of skinny and weak. Big, thick muscles were stacked on his body, fighting for space. On his short frame, they looked even more massive. His arms were easily twenty powerful inches around, and the rest of his body likewise impressive. He wore nothing but his shoes and underwear, the latter looking like it was about to burst. His ass filled the underwear in the back, as did the thick, manly genitals in the front. Jimmy was a beautiful young god of muscle, built for power. He laughed as he bounced his huge pecs, entranced by his new size and strength.