One thing was clear to Jeff: the size disparity between Dominic and Chris had become so great that he wasn't sure the latter would survive being fucked by his best bro. Yet he could hear them in the next room, Chris begging for just that, trying to convince his huge buddy that he would enjoy being railed by the muscleman's freaky cock.
The problem was that Jeff didn't want to dial back Dominic's size--he found it was insanely hot to watch Chris try to swallow the giant dick, and he imagined that watching them fuck would be even hotter! But he didn't want to make Chris big, either; the size disparity was half the fun! So instead he made a few custom changes to Chris using the Chronivac. Chris' ass became more flexible and resilient. It would be able to handle Dominic (and then some), yet would always return to its old shape when it wasn't being fucked. For good measure, Jeff made Chris' entire body more resilient and resistant to damage, just in case. The changes took effect just in time--Chris had finally convinced Dominic to fuck him, and the two of them were going at it in the next room, Chris crying out loudly as Dominic's unreal cock entered him.
Jeff snuck back over to the other room, and was treated to quite the sight. Chris was lying on his bed face down, his eyes wide and his mouth stretched into a large "o" shape. Dominic was looming over him, 450 pounds of brutally massive muscle, slowly pushing his thirteen-inch dick into Chris' accommodating hole. The huge muscleman grunted as he shoved his big tool home, and Chris cried out in pleasure as he was filled. "Fuck, you're tighter than my girlfriend!" Dominic growled as his huge dick went in to the hilt, every inch of it crammed inside Chris.
"Fuck me!" Chris gasped, "Nice and hard, Dom! I can take it! I can!"
"Really?" Dominic purred, clearly intrigued. He pulled his cock back, then pushed forward again with one short but powerful thrust. Chris cried out in pleasure, his fingers curling, gripping the bedsheets. "Oh yeah..." Dominic snickered, pulling back and repeating the process, harder the second time. Chris' low moan of approval made the huge man grin. He began to fuck Chris harder, his powerful hips thrusting hard, slamming his dick into Chris' ass over and over, as his little emo friend shrieked with delight. Dominic's breaths became heavy as he worked Chris over. "I've always wanted to cut loose!" he bellowed, finally able to fuck in a way that no woman would have allowed. He jackhammered his dick into Chris, slamming it home hard, over and over, until finally he let out a loud roar as he came, shooting his seed deep into Chris' guts.
As Dominic collapsed atop Chris' body, Jeff quietly returned to his own room. His dick was rock-hard again. Even though he'd cum a short time earlier, watching Dominic fuck Chris had really turned his crank. Jeff wanted to get in on the action. He sat down in front of the Chronivac. Perhaps it was time to make some changes to himself?