Ty's pussy ached with pain and pleasure as Chris roughly fucked him. Ty couldn't believe the change in his once good-natured friend, who was now turning into an evil, power-mad musclefreak. But Ty couldn't stop it either; couldn't... or wouldn't?
As Ty lay back and accepted Chris' energetic thrusts, he wondered how much of this was what he wanted, deep down. If he was brutally honest with himself, it probably was. He'd always had a crush on Chris. But there were times he thought Chris was a little too nice--not to him, of course, but to everyone else. And it's not like Ty had asked Chris if he wanted to have sex - he'd taken control of his friend's body and used him. And now that Chris was a huge bodybuilder with an even bigger dick than before and an attitude problem three miles wide, Ty couldn't deny that he liked it. Apparently, this was what he wanted...
And with that realization, Ty gave in to Chris' will. He turned his power over to fulfilling Chris' desires, and was rewarded by a bellow of lust and pleasure from his huge friend. "YEAH TY! THAT'S IT! MORE!!!" Chris roared, as his body began to expand again. His muscles bloated with size and power, growing beyond what any ordinary muscleman might possess. Chris' entire body grew, becoming taller and broader, making room for his expanding muscles. Ty put his small hands up against them, caressing and massaging them, feeling them grow under his fingers.
Chris' fucking became rougher as his strength increased, his ever-larger body able to drive his growing cock home with growing force. Ty cried out, the sensation of the being fucked by the growing rod was so intense. That only served to encourage Chris, who taunted his little friend. "That's it, slut. Scream for me!" Chris laughed, "But keep me growing, Ty. Always KEEP ME GROWING!"
Ty eagerly complied, sending waves of growth crashing into Chris. It was all too much for the behemoth, and with a mighty thrust he rammed his dick as far into Ty's pussy as it would go. Chris roared so loud the room shook, his huge cock exploding inside Ty, sending a massive wave of cum into his tiny fuckbuddy. The sensation was too much for Ty to bear, and he lost consciousness, overwhelmed by Chris' giant body and giant tool.
*
Several minutes later, Ty awoke. His now-empty pussy ached and his whole body was exhausted, but he felt quite satisfied as well. He rolled over to see Chris flexing in the mirror. Ty blinked several times, not sure if what he was seeing was real.
Chris was gigantic. Using his power, Ty could easily read the stats: seven feet tall, six hundred pounds of muscle, and a cock that reached fourteen inches when erect. Ty lay on the bed, watching Chris pose, hardly able to believe that his strange new power had produced something so big, so brutal, so... magnificent.
Chris saw that Ty was awake. The huge brute grinned with pleasure and turned to face Ty. "Like what you see?" he growled, his grin widening as he flexed his giant pecs for emphasis.