He kissed his brother on the mouth and stroked faster. Jamey was too weak to fight him off, and besides, the truth was he didn't want to.
"Mmph!" Timmy grunted, "I can feel it, it's happening, I'm growing again, and it feels so good! I want to be even bigger, Jamey, please let me grow, please, I need it so bad."
Jamey didn't respond, he couldn't. He was too busy moaning and trying not to blow his load, and besides, it was pretty clear what the answer was going to be.
"Fuck, it feels so good, Jamey," Timmy said, his voice was becoming more masculine by the second. "I love your big fucking cock so much, and your huge, beefy body."
Timmy was now as tall as Jamey, and nearly twice as broad, his arms and pecs swelling by the second, his back and shoulders stretching out, and his butt growing thicker, juicier, and rounder. Jamey couldn't help himself, he had to touch, had to feel his younger brother's rapidly expanding body, and the closer Timmy grew, the harder it was to resist.
"It feels good, doesn't it, big bro?," Timmy cooed, "It feels so fucking good to be bigger, stronger, hotter. Look at your little brother, he's getting so much bigger than you."
Timmy was right. The growth spurts were accelerating, and Timmy's growth was surpassing Jamey's by the second. He was already a good foot taller than his big bro, and he was only halfway through his transformation.
Timmy grinned as his abs bulged and flexed, growing even harder, his hips widening, and his butt bouncing and bubbling. Timmy let go of his big brother's dick and cupped his massive 34" chest, lifting his huge mounds up, the skin pulling tight and straining.
"I'm gonna grow even bigger," Timmy said, "And I'm gonna fill your ass with my big fucking cock, and you're gonna love every minute of it."
Jamey was too weak to speak. He watched as his younger brother grew and grew, the heat inside him building and building.
"You're gonna love it when your little brother fucks you. You're gonna beg for my big cock."
"Nnng," Jamey managed, his voice barely above a whisper.
Timmy's body continued to expand, his muscles becoming impossibly thick and defined, his abs turning into a perfect washboard, his arms and pecs bulging out, and his legs becoming a solid mass of muscle. Jamey was loony, unable to look away. He wanted it. He wanted all of it.
"I'm gonna cum," Timmy moaned, "And when I do, I'm gonna blow your fucking mind."
Jamey couldn't hold back any longer. He was powerless against his younger brother's will. His cock erupted, spraying his seed all over Timmy's giant pecs.
"That's right, bro, cum for me," Timmy commanded, his voice now a deep, powerful baritone.
Jamey felt the heat inside him reaching a boiling point, and the pressure building in his nuts, begging for release.
"Cum for your big, beefy, muscly, sexy brother."
Timmy's body was now the pinnacle of male perfection. He was taller than Jamey, wider, and packed with more muscle than anyone had ever seen. Jamey felt the heat inside him rising, and his cock erupting, spraying his seed all over Timmy's rock-hard body.
"Cum for me, bro. Cum for me."
Timmy's body was a work of art. Every muscle was perfectly defined, and every inch of his skin was covered in a light sheen of sweat.