"Thirteen's a fun age. Time when life's changing so much, when you start experimenting...you know, with stuff." I would be old enough to do sports and stuff, but young enough where I don't have too many responsibilities. It might be fun to experience the early days of puberty again," said Mike after some thought.
"Okay..."
Jeff entered in 13 for Mike's new age and a pop-up appeared.
"What's that?" asked Mike.
"It's a message saying that to make you that age the Chronivac will have to edit your relationship with the family and alter reality."
"Edit my relationship with the family?" asked Mike.
"Yeah, from father to younger brother. Maybe this isn't a good idea."
"It's fine. I don't mind being your little brother if you don't mind having one for a little while."
"Define little while," said Jeff.
"A weekend or so?"
Jeff sighed. "Okay, but just so long as you're not being my 'bratty little brother'," joked Jeff as he pulled up Mike's profile.
"No promises there, Jeff, though it might help if you keep my adult memories in tact so I can have some possibility of restraining myself," suggested Mike with a rather impish grin.
Jeff accepted the suggestion and the prompt disappeared and Jeff was allowed to select for Mike to keep his memories and for reality to alter to make him his little brother. Jeff also made sure that his memory of this reality would be preserved as well, and then he hit accept.
"Whoa..." said Mike a few seconds after Jeff had hit the accept button.
"What is it?"
I just felt a warm... pleasurable... pulse through my body... d-damn... there it is again..." said Mike, grabbing onto the back of Jeff's chair. Jeff rose and looked at Mike. For a man in his late thirties, he wasn't half bad looking. He was clearly a thicker man who'd clearly let himself go a few years ago and was now a bit husky in addition to his hulk. However as Jeff stared, his father's slight pouch of a belly seemed to be shrinking, and the thickness to his body seemed to slowly be decreasing, like a balloon slowly deflating all at once. The pulses seemed to gain in intensity and were likely waves of youth returning to Mike. Already, his dad Jeff estimated looked closer to his early thirties now than he had a few moments ago. With a third waves of pleasure, gone was the pouch, and the shorts that had been on the tighter side now looked a little loose, if not sliding down a bit. His shirt seemed to be filled out a bit more, as Jeff's memories of his younger buffer dad from about a decade ago seemed to resonate with the younger man standing before him.
However the transformation was far from over, and the waves of pleasure seemed to intensify as he re-entered his twenties and started looking more and more like a young adult rather than a father of three. Body hair was beginning to thin a bit as second puberty undid itself, not leaving him without any hair, but far less than he had had moments ago. The beard his dad had acquired over the years was now close-trimmed and far less bushy looking. Muscles bulged while his body's thickness thinned out, soon a rather athletic looking young college stud was standing in Jeff's room. And it was about now that Jeff found he couldn't rightly think of the man standing in front of him as his Dad anymore, but instead was starting to think of him as his older cousin Mike.
"My head's starting to ache a bit..." complained Mike as he placed his hands up on his temples.
"I think it's reality changing... you're more Mike to me now than Dad," said Jeff.
"Right... but I also feel like I'm forgetting things... like col---I mean High School," said Mike as his muscles deflated even more dramatically now and he dropped an inch or two as he left his twenties, his beard sank back into his face and his body hair seemed to shrink to just some hair on his arms, his legs, and a bit of scruff on his face that was all quickly lightening, shrinking, softening, and turning to peach fuzz. Soon Jeff could only see his brother, not a cousin, but his twin brother Mike.
The next wave apparently was the most pleasurable as Mike moaned out in what sounded like pure ecstasy as the now teenage Mike lost all muscular definition to become a bean pole with overly large hands and feet for a moment before his voice cracked and the growth spurt... uhhh shrink spurt? Yeah, shrink spurt. ... the shrink spurt caused Mike to be sent straight from being a teenager to a preteen. At this point, Mike's adult clothes which had more or less remained on his body, despite sagging or stretching as he'd changed his workout routine over the years, suddenly seemed to bag on him. His adult shorts and boxers dropped to the floor, though his now stretched out shirt just barely bagged over himself to give him modesty, though it seemed that last wave was pleasurable enough to cause his Dad to cum all over his dropped shorts and boxers.
"Oh no... I had a wet... uhh... I... uhh... forget what I had..." bemoaned Mike as his voice finished cracking and settled back into a boyish octave, and Jeff could see Mike as nothing more than his little brother now.
However as the laughter continued, a shimmer seemed to occur throughout the room as pictures changed. No longer were photos of Mike with the family as Dad there. Some other man was there in his place--a man who looked suspiciously like Uncle Eric--no... Dad, Jeff corrected himself. Uncle Eric was his Dad now. In the old reality Uncle Eric hadn't ever been married, instead choosing to be a life-long bachelor--or so his family had said. But in this reality, Eric had met Jeff's mom and married her instead of Mike, and thus Jeff and his siblings--which now included his "oops" brother Mikey as the much younger baby brother still existed. The adult Mike disappeared from photos before Mikey's new birth date, and in photos where he was alive, he now shifted into being the baby and little boy of the family.
Meanwhile Mikey's former adult clothes shimmered themselves, shifted, and reappeared on Mikey as age appropriate clothes for a thirteen year old. The cum he'd expelled while growing younger vanishing at the same time.
"Hey Mikey, you good?" asked Jeff, the name Mikey just feeling natural to call his little brother now.
Without missing a beat, Mikey sat up with a big grin. "Yep Jeff! This is the best thing that ever happened to me!"
He blushed looking down at himself, "Uhm, could you teach me ...about girls and grown up stuff?"