As soon as Aidan had pointed out the lube slick on your small nub, he did what any and all twelve year old boys are apt to do: touch something without thinking if it will be something he regrets later. There was no real concept of later, only now, and now little Andy had something slick on his privates.
"Is it baby oil or something? Oh...
"Ow..." you said in response to Aidan's touch, in which a static shock exchanged between the two of you.
"Wow, it feels kinda warm to touch, kinda like icyhot," said Aidan as he pulled his hand away from the spot of lube he'd touched and looking at his own hand intently as he moved his fingers over the lube--unintentionally rubbing it into him.
It took a few seconds, but both you and Aidan suddenly went erect, with your tiny nub poking up straight much quicker than Aidan's slowly tenting basketball shorts.
"What? Why do I feel... oh..." started Aidan, before his hand that had touched the lube unconsciously wormed its way under the elastic of his shorts and around his early pubescent cock. Having been through it before, you wondered what was about to happen--would you grow to be Aidan's twin or would he shrink to be your twin? Clearly the condoms weren't what was causing the change themselves--but the lube inside them were, if Aidan could have a reaction just from poking at the lube. But these thoughts weren't flying through your head, as your tiny toddler fist encircled your nub of a member. Your questions seemed to be answered as you felt the tingling from your lube slathered member spread through the rest of your both, and your dick begin to grow and push through your three year old fist, before your hand began to catch up with it in size. This was soon followed by the feeling of your legs stretching and sliding down the side of your bed, eventually coming to rest on the floor just as you felt the release of what felt to be a quickie. With that came the pleasant rush of hormones that caused you to sigh in satisfaction and lay back on the bed, satisfied with the small amount of droplets that had escaped your member.
It was only in the dissipation of this high that you thought to see what had happened to Aidan, and as such you turned your head to see laying on the bed next to you was a three year old toddler who'd passed out from the pleasure, and quite clearly was Aidan, reduced to toddler size and stature. His clothes having shrunk and changed along with him, turning into toddler shorts which barely covered the pull ups beneath them, and his t-shirt becoming a Blues Clues print. His socks having turned into cute anklet socks with rubberized hospital sock padding on the bottom to help with traction. His shoes had remained on the floor, with him having shrunk out of them, and now you recognized them as your shoes and not Aidan's.
Curious as to your own transformation, you stood up and hurried over to your room's mirror that was located on the back of your door. You were still red-haired and blue-eyed, you just looked like Andy at an older age, 12 years old and at the beginnings of puberty, if the few hairs in your armpits and above your early adolescent nub were to be trusted. You were a little lanky and skinny but no longer frail looking, with your feet and hands a little bigger proportionally than they should be, indicating that puberty was shortly on its way. The freckles Andy had had at age three had only continued to multiply, giving your face a bespeckled appearance. You had grown into Andy's ears, which looked less noticeable, and your shaggy red hair had remained as such--if not looking particularly thicker than it had when Andy was a toddler.
Your room had transformed yet again, this time from a toddler's bedroom, to that of an older boy's room. Messy, but with toys, clothes, comic books, and other such debris piled about the floor.
Just then, you hear a set of footfalls coming up the stairs, followed by a call for Aidan from what your new memories are telling you was your Mom.