Jeff was working on geometry homework stroking his goatee absentmindedly, because he could... The reality change made it so nobody saw him any different from last week, though in truth, he only had peach fuzz last week and despite his desire for them, even his sideburns, the first burgeoning signs of manhood, were pathetic. Today though, he had a full goatee and now, a solid 5 o'clock shadow had set in even though it was only 3:15... Jeff had not missed an opportunity to examine himself in the mirror and most of those times, even at school, ended in self fulfillment.
A beep at the computer roused Jeff from his studies. Setting aside his homework he jiggled the mouse and a moment later the computer sprung to life. A trail of popups all said the same thing, "Reality Modification did not complete as expected. Correcting... Correction completed. Have a great day."
Jeff reached over and took a hit from his vape pen not sure what the Chronivac had modified, or failed to modify the first 50 times around. Nobody freaked about his facial hair and that's all he cared about.
The package Jeff used was a carry over from Chronivac 2.5, it stored full profiles of about 50 people for each gender to set the standard for each level of, in this case, hair. It was patched to work with the Chronivac 3.0 again for the 3.5, and now once more for the 4.0. The beta reality alteration engine making the Chronivac 4.0 had no problem looking at the 50 male profiles, averaging the results, and applying it. However the underlying patch modules, when applying a reality alteration, tries to fully justify the alteration however necessary. To make it normal for Jeff to have as much hair as he does.
The program first changed people's concept of what the current Jeff is and has been. This changed pictures, gave him an electric shaver two Christmas' ago when his parents caved and let him style it rather than demanding he shave it off, and sprinkled the bathroom floor and around the sink with shed body hair and escaped hair trimmings, as well as the rest of the house.
The 4.0 version leaves it at that, this is normal now... done. So the safeguard kicked in limiting what the old program could do. Problem solved. Except that halting the process was logged as an error instead of an override which caused the module to re-evaluate what needed to change, build a new reality, and try to apply it. With Jeff already having the level of hair needed, the program focused on justifying it for reality's sake. The 4.0 overlay realized that unnecessary reality alterations were requested and kept shutting them down causing this cycle. But without the initial change needing to be applied, depending on the complexity of the change, the AI didn't always have time to evaluate everything before alterations began.
So Jeff didn't become a 25 year old stoner musician living at home and working fast food with no intention to ever get a "real job", but he now vapes like one. He didn't become an overweight 35 year old single biker who "probably had a couple kids out there", but he does have a chest tattoo now. Jeff nearly became the 19 year old varsity quarterback star for his school, and because it was so (relatively) close to his existing life, he did gain around 40 lbs of muscle bringing him up to a muscular 170 instead of 130, but he doesn't play sports or lift weights.
With each cycle that gets a change in, the successive attempts either try to justify, alter, or undo the other anachronisms but the more wildly different the new end result is, the less likely it is to process a change. What will Jeff be when this process finishes