Tom was thinking of heading to the park, but the sight of his now very muscular little brother made him envious. He didn't want to take them away, he just didn't want to be a little runt amongst a bunch of muscle giants. So with that in mind he pulled off his white t-shirt and stood in front of his bedroom mirror in just his blue pyjama pants and eyed his thin frame. Though despite his lack of muscle he still had a good face, with dirty blond hair, blue-grey eyes and a boyish charm that remained even as he grew towards puberty. "Well, it's now or never," he muttered and, with a brief flourish, he fired the wand at the mirror.
The bolt of energy bounced off the mirror and right into his body, and immediately he felt a soothing warmth all across his body, though all his muscles also tensed up like when Jake had gotten hit. Then each and every muscle grew simultaneously. His pecs bulged out into firm, hard slabs of muscle over a solid, perfectly defined six-pack while his lats grew and spread until he had a perfect v-shaped back of rock hard muscle. His deltoids became round and hard and his biceps became thick pythons of muscle. His legs became thicker and harder while his calves bulged out and his pyjama pants became stretched to the limit before reality shifted and grew them.
It only took the transformation a few seconds to finish, and when it had Tom looked in the mirror to see an extremely well muscled fourteen-year old looking back at him. He took a moment to flex every muscle, particularly admiring his perfect abs and solid biceps. He was definitely larger than Jake again, though since his older age played into that he figured he was probably about equally muscled from a proportional view. He could feel the extra strength running through his limbs and it felt amazing.
"Oh um," Jake said, appearing back in the room with his gym bag slung over his large shoulders, "Do you wanna come with?"
"Um, I'll drop by later," Tom replied, his voice a bit deeper now thanks to his larger chest, "I want to spin by the park first."
"Ohhh, what's her name?" Jake teased.
"It's not that, I just want to go for a walk," Tom replied.
"I know, I'm kidding. I hope I manage to keep my size by the time I'm your age, the girls fall all over you."
Tom shrugged his large shoulders in response, "I have to change, catch you later Jake."
Jake left and Tom quickly changed into a large tank top and sports shorts before dashing off to the park, delighting in his new speed from stronger legs. It wasn't far from his house, an easy jog for his newly strengthened body.
When Tom got to the park he looked around for more people to practice the wand on. There were several kids on the playground structure, probably about six years old each, and some kids about his age, maybe a couple years younger, on the court playing basketball. Then finally there were some people skateboarding of various ages, from younger than him to older. The question was, who should he target?