Alan got an excited smile on his face. "I'd like to try it! As I said, I think it could be fun, and even if it's just for the weekend, it'll be nice to go back to old times!"
The other boy nodded, "Well, alright then. But don't do anything too crazy, I'll still have to supervise," Jeff reminds him, before turning to the Chronivac. He opens up Alan's profile, going to the age field. "Last chance to back out."
Alan said nothing, so Jeff erased the current age field, typing Lucy's age of 6 in its place. The Chronivac auto-adjusted details like height and weight. He then moved to the duration field and set the changes to end Sunday evening, which should leave more than enough time for Alan to be alone when the transformation wears off. "Alright, here we go." Jeff announced. "Three..." He began to count, moving to the confirm button. "Two..." With his mouse hovering over the button, he took a deep breath... "One!" Then, he clicked, and turned back toward his friend.
With the changes confirmed, Alan shuddered, feeling a tingling sensation surge through his body. His body began to shrink, slow and steady at first, but rapidly increasing. "Woah, it's actually happening!" The regressing boy exclaimed, his voice squeaky as he's going backwards through puberty. An uncomfortable cramp makes itself known in his groin, as his genitals revert to their prepubescent state. "Agh, that feels weird..."
Soon enough, the changes conclude, Alan's clothes changing last. Standing before Jeff is now a 6-year-old boy, slightly shorter than his sister, much to his amusement. "Heh, you're shorter than Lucy now." He points out with a smirk, watching as the younger boy looks over his own body.
"Wh- Huh?!" The child's gaze suddenly snaps to the older boy. "Why did you make me smaller than her?!" He asked, and Jeff responded by shaking his head.
"I didn't." He answered. "I didn't touch your height, that was all on the Chronivac." He chuckled a bit, seeing the pout that formed on Alan's face. "Anyway. Wanna do anything else to pass the time until the sleepover? Or would you rather go see Lucy now?"