Jake saw what Ryan pulled out of the bag, a tiny bottle of purple liquid. "Drink this," said Ryan.
Jake took it, unscrewed the cap, and downed it all without even pausing for breath. Then he read the label on the bottle. 'Old Salty's Smoother and Rejuvinater'.
"You'll see what it does," said Ryan, taking the bottle. "It's already working."
Jake looked down, and saw that his hair was pulling back inside his body. His treasure trail was gone almost immediately, and his leg hairs went next, followed by his armpit hair. Jake looked between his legs, knowing what was coming next, and sure enough, his wispy pubes soon vanished, leaving him bald as Ryan must be. Then it got worse.
His dick shriveled, becoming smaller, and his balls pulled upward as well, and soon he was left with a puny little boy cock. Jake was furious.
"This better not be permanent, master!"
"Or what?" asked Ryan.
"Or...I'll..." Jake gave up. There was nothing he could do to Ryan.
"I have more hair than you now," said Ryan. He pulled down his pants, and Jake had to lean in to see. Ryan didn't really have pubes, but his pubis was a little fuzzy with light hair like Jake had had on his arms. Ryan's dick looked a little bigger too.
"This is so unfair! I didn't do anything like this to you master!"
"Were you planning to put the collar on me again?" asked Ryan.
"Yes, master," said Jake, shame faced.
"So I think this is fair," said Ryan. "Now, come over here and suck on my cock."
Jake was disgusted, but obediently started to blow his little brother's dick, which was sadly now bigger than his own. Jake was familiar with the general idea, and somewhere in the back of his mind he knew he'd have made Ryan do it if their places were reversed. Jake slurped loudly on the small cock, which fit completely in his mouth. Ryan was enjoying it.
Jake knew he'd done it right when Ryan told him, "Yeah, keep doing it just like that, here it comes."
Ryan's little drop of cum splashed into Jake's mouth, and he wanted to spit it out, but he kept sucking and swallowed it down.
"Stop," said Ryan. "Keep your mouth on it while I play video games."
For the next two hours, Jake was trapped on his knees, breathing warm breath on his brother's dick, smelling Ryan's unwashed crotch the whole time.
Ryan made him blow him whenever he got hard again, which was three more times while Jake was down there.
When it was time for bed, Ryan gave another order, "Crawl whenever you're at home, unless you need to stand for using the toilet or brushing your teeth or whatever, but crawl the rest of the time. You can go now."
Jake, ashamed and defeated, crawled on his hands and knees out of his brother's room.
When he laid down in bed, still naked, he knew there was no escape. He'd be his little brother's slave until Ryan got tired of him, and maybe longer than that. And would the potion's effects ever wear off, or was he going to have a tiny hairless dick for the rest of his life? His hope was running out, so he cried himself to sleep, not even able to jerk his little dick to orgasm without his master's permission.
When he woke up, his little brother was in his room. What was he going to tell him to do now?