"Why?" Hiro asked. His smile became a scowl. "Because to you, I was just a fuck toy, Guy. Something to get your big cock off!" Hiro's huge chest flexed involuntarily as his voice rose, showing off the deep striations that ran across the big slabs of beef.
"N- no!" Guy stammered, "I mean, yes, the sex was fun, but I-"
"But nothing!" Hiro roared, stepping into the bathroom, barely able to get his massive bulk through the doorway. "You would have used anyone to get off!" Hiro was absolutely irrational, no longer remembering how Guy had said that he'd always had a crush on Hiro, no longer remembering all the times he had secretly wished that Guy would fuck him nice and hard.
"But now the shoe is on the other foot," Hiro growled menacingly. The crotch of his skin-tight shorts bulged as he grew hard. A wicked grin came over Hiro's face, and he slowly licked his lips. "Forget the clothes," he said, "I think I need you naked a little longer..."
Guy squealed in fright, but Hiro lunged forward, picking up the smaller man, carrying him out of the bathroom and into the bedroom. He flung Guy onto the bed, snarling wordlessly. Guy landed and scooted back to the headboard, his eyes wide. A lust-filled, wicked smile spread across Hiro's face, which contorted into a grinning grimace. Slowly, Hiro began to swell, his already large body bloating with powerful muscle, his frame lengthening, broadening, thickening freakishly. The pajama top became even tighter on his torso, the sleeves splitting as his massive arms ripped through them. His already tight shorts strained and tore, fluttering to the ground in tatters, letting his big, growing cock and balls hang free.
Hiro growled, and tore the last shreds of cloth from his massive body. He grinned, an insane glint in his eye, as he rose up to his full height. At ten feet, he was taller than Guy had been, his muscles were bigger, and his cock was definitely superior, at nineteen hard inches. Guy, seeing Hiro's immense size and impressive arousal, tried to flee. He was quickly blocked by his massive roommate.
"Oh no, Guy," Hiro chided cruelly, "We're going to have fun..."
Hiro roughly snatched up Guy and carried him to the bed and placed him upon it, easily holding the smaller man down with his superior strength. Guy was strangely aroused by the whole thing, his own cock growing hard with excitement. Still, he struggled futilely against Hiro, fearing what such a huge body would do to him.
The massive man just laughed at Guy's pathetic attempts to escape. "Sorry, little wuss," he teased, "But I've got some pressure building up here, and I've just got to relive it!" Hiro's huge cock throbbed excitedly. "Besides," the musclefreak purred, "I can tell you want this too!" He gave Guy's hard cock a pointed look. He then positioned his huge tool at Guy's rear entrance, grinning lustfully. "Time for payback, Guy!" he grunted, as he forced the big rod up the smaller man's ass. Guy writhed as the monster muscledick split him apart, but he knew better than to try to resist - Hiro was much too strong for that.
For his part, Hiro smiled savagely as he began to push in further, thrusting in with his powerful legs, forcing more and more of his big meat up Guy. "Take it," he growled, as he rammed more insistently. Guy moaned softly, then began to yelp as Hiro began to hit home in earnest, pummeling Guy's spot mercilessly, sending ecstatic agony through the smaller man. Hiro kept the pace up, ramming in faster and harder, until finally he exploded inside Guy's ass, filling it with hot, thick cum. Hiro continued to pump, until every last drop was out. He collapsed atop Guy, breathing heavily, a satisfied grin on his face.