A fun, colorful pattern appeared on his face as the Chronivac glitched out a bit, somehow managing to shift reality on it's own. However, due to the box not actually being ticked, it didn't obey the usual rules for when it shifts reality.
Jeff's room had changed around him, looking more like a larger version of his little sister's room. Meanwhile, what was actually his sister's room had been cleared out, turning into a spare bedroom as all of her stuff moved into Jeff's former room, replacing what he had.
"Huh? Why's everything changing?" He then realized that, despite being a diaper, he could somehow still speak. "Wait, that's weird... I don't even have a mouth!"
The timeline shifted, the chronivac trying to modify reality without removing anything major, such as his birth. While Jeff didn't know it, his entire life had been changed drastically, and his age had been modified to match his sister's perfectly.
Gone was his original life, and in came the new. Seven years prior, when his sister was born, reality had been shifted, having her born already wearing a diaper; This stumped the doctors, and not even a team of scientists were able to figure it out right away.
The diaper his sister, Eliza, was wearing happened to be Jeff, who was now her twin brother. They've lived that way ever since, and despite Jeff still taking on quite a few humanoid qualities, he'd been able to live content between Eliza's legs all his life.
He survived off of eating or drinking Eliza's excrements, with it being more filling to his diapered body. Overall, they had a great relationship, with Eliza feeding Jeff while he kept her clean in the lower areas.
One known thing though was that he'd still have to pee, and when doing so he often hit Eliza's genitals by mistake, causing a chain reaction where Eliza ends up letting it out as well. Overall though, neither minded when this occurred.
His pattern had changed with his emotions, with it commonly being happy and cheerful. At this point, however, Jeff was confused on why his room had changed, with the pattern changing to show a confused cat on the front.
Eliza had walked into the room, calling out for him. She spotted him on the floor, and ran over. "There you are! I was so worried..." She picked him up and hugged him close, with Jeff, unaware of the changes, still being confused.
She broke the hug, sitting down. "Let's get you back on!" She lowered Jeff down to her legs, sticking her legs through. It felt weird for him, as he slid up her legs and under her skirt, where she previously had no underwear on. With a giggle, she used a mirror to make sure he was nice and snug, before...