The look on Kyle's face was almost feral, a wild look of dominance streaked across his hypermasculinized face, his canines almost bared like fangs. It was a look that could freeze most people in fear or lust, and to Aaron, it inspired both. The hulking boy-made-man-made-something-beyond grasped at his titanic length, a 21" spire of meat. So heavy, it bent slightly in the middle as Kyle stroked it to the base, his dangling, heavy nuts jostling with the motion, full and pregnant with his seed.
He slapped the giant rod against Aaron's smooth jaw, the smaller, older brother taking the colossal thing into his comparatively tiny hands. Gripped around the base of the head of the musclefreak's cock, he couldn't even close his hands all the way around it. Kyle roared as he felt the soft lips of his brother enclose around the tip, reveling in the way Aaron had opened his jaw as wide as he could and still had to open it wider, wincing through the action. His brother had become skilled over the weeks at taking his giant tool, of worshiping his growing body, but today felt different. It was like Aaron's tongue was electrified, the lightest touch almost enough to send the beast of a man over the edge.
Kyle roughly pushed his brother off his cock, snorting atavistically, like that of a bull. His hands curled into fists, his knuckles going white as he held his orgasm at bay. He didn't want to finish in Aaron's mouth this morning. His breathing slows as he feels the moment passing, his giant cock leaking copious amounts of pre-seed, a small stream that would rival a grown man pissing, dripping all over his brother's lower torso. Without ceremony, he grabs at Aaron's toned thighs, lifting him up and impaling his cock right into his brother.
The beast moaned lowly, surprised by the ease of which his cock slid right into Aaron, it was like the smaller guy was made to take his cock. But even more of a surprise was just how tight it felt. Even when his brother had regressed into a complete wimp, it wasn't this tight. He bucked forward, a low bellow sounding his pleasure. "Oh fuck, take it, ya little bitch..." He looked down and saw the expression on Aaron's face. He leaned over, his pecs otherwise being in the way with just how extreme his bulk had become. Aaron's expression was twisted in a grimace of rapture, the smaller twunk baying lightly as Kyle's gigantic cock spread his ass and innards wide open. The behemoth grinned as he watched as the smaller guy grasped at his own length, his big, but comparatively tiny, 9.5" tool pulsing with his heartbeat.
Aaron also noticed that something had changed between the two of them. His cheeks flushed as he felt his body move on its own, his ass greedily pushing down onto Kyle's girth. The smaller brother arced his back, his toes curling as he came. Great bursts of seed splashed all over him, so much pressure that the first jet blasted past his own face and made a loud splat against his headboard. The second glazed his face and the rest pooled between his slightly developed pecs and the hint of a six-pack forming. It drove Kyle wild.
The musclebeast had seen plenty of guys cum all over themselves. But, the way his brother creamed himself, the way it felt with each contraction around his meat, he couldn't help it. He hunkered over and lifted his hips, plunging his cock all the way into Kyle's ass, his balls pulled up and he roared as he filled his 'little' big brother over and over as he bred him. He leaned over and slurped up Aaron's seed, hungry for its flavor. Aaron had made so much now that his equipment had been fully restored. No wonder having his brother's hormones for a month jumpstarted his growth!
Both brothers moaned lowly as Kyle pulled out, the two of them both feeling a sort of emptiness, like a key missing its hole. For the first time, Kyle actually felt an odd sense of satisfaction. His balls usually always ached for more. But now, he leaned over and took his brother's cock in his mouth. That taste, it was better than his own! He'd gotten used to sucking himself off at school, the other students and teachers knowing full well that they had to vacate the hallway adjacent to the janitor's closet to spare themselves from listening to the beast pleasure himself in there.
Aaron moaned as his brother sucked him off, the teen gurgling on his own spit as he was sent into sensory overload. He'd masturbated so many times before, but this sensation was new; heck, ever since he'd gotten his endowment back, everything felt... more alive, like he was finally living with all the colors in his previously drab world. The smaller guy's hands gripped onto the sides of Kyle's head, his fingers playing with the soft beard hair, the same hairs that tickled him when Kyle went all the way down on him. He whined and blew a load into Kyle's mouth and the giant gulped down his seed with gusto.
After his cum-meal, the giant stood and grinned, a strand of Aaron's cum congealed on his thick beard. "Thanks for the pre-workout, bitch," Kyle chuckled before hauling the smaller guy over his shoulder. The giant ordered Aaron around like he always did. 'Make me shakes. Feed me, bitch. Just try to spot, if you can, runt!' Only, this time, it was turning the older brother on.
He still had to massage his brother's mighty tool, fondle his balls and worship his Herculean physique, only this time, Aaron was also buck naked and rock hard himself while doing so. It only seemed to spur Kyle on more when his massive muscles would rub against his brother's puny 9.5" cock in the middle of a set and send the athletic guy over the edge. After re-racking, he'd rub Aaron's load all over his swollen form, the cum glistening on his burgeoning muscles. He liked to imagine that all the testosterone Aaron's balls made leached into his cum and was now infused into him.
For hours, Kyle lifted, his body swelling with more and more mass as he pumped his muscles full of blood and his face full of food. By the evening, it was clear to the both of them, Kyle was still growing. A heavy feeling sank in Aaron's chest, realizing that it wasn't just the switch of his cock and balls that caused his brother's growth. No, that was merely the catalyst, the surge of hormones and Madame Illusia's magic had jumpstarted Kyle's puberty, sent it into overdrive and the beast had all of his adolescence to ride it to ever increasing sizes...
After a night of brutal fucking, the 'bitch' of the relationship went to bed. And to his surprise, his gargantuan brother collapsed beside him, tuckered out from taking Aaron so relentlessly. Their mother popped her head in, remarking how cute that they were still doing sleepovers at their age. Aaron was aghast, could she not see all the cum, that her youngest son was a freak with a massive erection, that her eldest had a river of musclefreak spunk dribbling out of his ass? As she bid them goodnight, Aaron knew he had to do something, maybe go back to Madame Illusia's and try to fix this... but first... he needed sleep.
The next morning...