Drok grunted as he ran, and could feel his hand edging closer to his immense cock. But he made it, just in time.
Without a second thought, Drok grabbed the nearest low-hanging fruit, and immediately bit into it. Derrick almost gagged at the taste - like a combination of dirt, cum, and... delicious watermelon? Derrick moaned in delight as the fruit immediately began to taste sweeter than any fruit he'd ever had before. And the flavour kept shifting - one moment, it was a juicy mango, the next it was the sharp taste of pineapple, then to some exotic fruit flavour that he guessed probably came from somewhere in Asia.
Derrick felt his mind stabilise immediately - Drok was still there, a part of him, but no longer would Drok be tempted to complete his transformation. No, Derrick had saved his mind, his very identity, and with no time to spare. He looked down and found his hand caressing his footlong dick, yellow precum drooling everywhere. Just seconds longer, and Drok would have been masturbating right in front of the fruit, before heading back to that cave and Grok's ministrations.
"Me made it" Derrick said, before pausing and searching his mind. The right words were there, but he couldn't quite sort through them to get the right one, yet. It was a start, though.
Another bite of the fruit, which, given the odd initial taste, he was thinking of as "Fruit of the Earth", and Derrick felt pain shoot through his body, knocking him to his knees. Instinctively, he grabbed at the ground, and felt a power flow up into him through his hands. He watched, a grimace on his face, as first his hands, then his forearms began to grow. He could feel his legs similarly swelling, his cock actually expanding further along with them.
As the weighty appendage drooped towards the ground under its own mass, and made contact with the earthy soil, he felt even more power flow into him. He groaned as his body stretched out in all directions, and then moaned deeply as his long-held-off orgasm hit, his yellow caveman seed pumping out of his still-growing, baseball-bat-sized member, before being replaced by a much more golden seed.
Derrick couldn't help it - he got some of the seed, mixed with some dirt, onto his hand, and tasted it. It tasted so much like the fruit, he couldn't help but get more.
The flow of power from the ground having dwindled to nothing, Derrick stood up, and up, and up. When he first got to the tree, the lowest fruit was barely within reach. Now, he found himself looking down slightly at it. If he had to guess, he was a solid 8 feet tall, now. A look over his body confirmed the sensations he had gotten earlier - he was bigger in all directions - his muscles had grown in, and then some. He felt truly powerful.
"Me am... I am huge!" Derrick exclaimed, and then smiled at his words coming back to him. The part of him that was Drok was also pleased, at the magnificent appendage and the manly muscles. After a moment, Derrick realised that the loincloth had been forced off his body during his growth - he looked at it and watched as it seemed to disintegrate before his eyes.
A convenient stream ran nearby, and Derrick had to see what had become of his face. With a small amount of disappointment, Derrick found Drok's face looking back at him. So the effects of the loincloth hadn't completely worn off.
Derrick reached for another fruit, before a thought came to him. He was incredibly happy with his body as it was. His mind was intact, he had grown into a powerful man (or was it a tiny giant?), and he had a wonderful tool at his disposal. At that thought, Derrick squeezed his now-flaccid tool and smiled. He could live with a caveman face. But what happens now? What happens if he eats another fruit? Did he really want to become a real giant? And would he end up with six arms? What has happened to his family? Have they all changed into something, too? Or was that Derrick's fate alone?
If he grew much further, he might be able to leave the Cyzicus Room, but he wouldn't get far down the corridor before it became too cramped. So he had a choice - finish what he started and continue eating fruit, or return to the door (and then to the front desk) to enquire about his family.