Ty spots a teen walking through the front door of the gym. He shows his ID to the lady at the counter, but she says that his membership has expired. Ty gets a good look at the teen and decides that he could have some fun with him, since he recognizes the boy from school. Ty wishes for the information on the boy's membership card to change so that his membership is suddenly valid, and the lady behind the counter lets him through.
The teenager, who is 15 years old, walks in carrying his gym bag. His name is Zack, he is 5 ft 2" and he has short, black, spikey hair. The teen is athletic but not very muscular. Ty waits patiently for Zack to walk into the locker room and to remove his sweats.
Zack changes and comes out of the locker room. Then, he runs on the treadmill, he pedals on the bike, and he does the stair-climb machine. Finally, he does the bench press and he does a few calf raises before he returns to the locker room in order to take a shower. He doesn't realize that Ty was following him.
After a few moments, Ty slips into the locker room and sees someone in the showers. Using his x-ray vision, he sees that it is Zack. Just as Zack comes out and gets all dried off, using his towel, Ty decides to use his powers on the boy.
Zack was about to slip into his jockstrap when he felt an odd tingling, which struck just about EVERYWHERE in his body, especially his muscles. Then, out of nowhere, his chest began to bulge! His flat pectorals hardened and suddenly ballooned out from his chest, filling out as they rapidly pushed out forward and sideways all at once! Zack didn't know what was happening to him, and looked down in confusion as his growing pectorals grew outward and forwards, becoming two mighty globes of hard, round muscle!
"What the hell?" he wondered, as he felt the increased weight in his chest.
While running his hands over his big, round pecs, his biceps suddenly began to inflate as well, filling out as they became round and large, like canteloupes! He moaned softly as he felt the strength in his arms increase all at once! He clenched his fists and was forced to flex his arms at the same time while he was overcome by a sudden surge in power in his thickening arms.
"Uhhh.... Holy crap... What is happening?"
Next, Zack's flat stomach turned into mighty abs like tiles on the kitchen wall. Buttons popped up on his stomach like powerful abdominals! His stomach pulled in, showing the outline of his rib cage, the way most bodybuilders like it, while his torso widened even more. Just above his stomach, on either side and just below his arms, mighty lats formed which spread out like wings. They were so thick and so wide, that they made him look like he wore a cape that was draped behind his back!
Lastly, Zack's legs started to grow as well. His calves ballooned out just as his quads on both legs began to inflate, all at once. His calves began to push outwards and sideways at the same time, practically growing towards one another and becoming to thick and so wide, that Zack wouldn't be able to stand with his legs placed next to each other. His calves grew from tennis balls to the size of soccer balls, inflating at a tremendous rate while his quads thickened and widened at the same time, just above the knees and below his waist. They widened and grew so wide, much wider than the rest of his upper body, that Zack would have to adjust the way he was standing!
Finally, Ty decided to grow Zack's 4-inch manhood and make it double in length as well. After all, the boy needed to be big everywhere! His balls grew to the size of ping pong balls so that they matched the bigger manhood. All in all, Ty was happy with the results of his little growth spurt, and he decided to wait for Zack to finish getting dressed. He used his powers to enlarge all of Zack's clothes in order to fit his bigger, muscular body, so that clothing wouldn't be a problem.
"Hey there, big guy!" Ty grinned, as zack emerged from the locker room. "How's going? How was the workout?"
"Hey there, Ty! I was almost afraid I couldn't work out today but for some reason, they accepted my membership card!" Zack replied.
"Well, you need the gym, dude! You gotta take care of those big muscles of yours!" Ty grinned.
"Uhh... Yeah, I guess..." Zack replied shyly.
Ty liked Zack. He had always been nice to him in class, and now that he was big and buff, he was still nice to him. Ty just looked at the muscular guy and wondered what to do next? Should he make Zack even bigger? Ask him if he had any other siblings he would like to see become any bigger? Or maybe grow some of Zack's friends?