A while back.
Your little brother frowned as he watched his three best friends travel upstairs with his older brother. Using a magical doll, he was able to make them all a bit older.
After holding the doll for several minutes, venting with anger, your little brother tossed his toy truck, how dare his friends to betray him like that, and how dare his older brother to ruin his slumber party!
Just then, he heard a small knock from the front door. Thinking that it might be his mom returning home after sending his own perils, he hastily opened the front entrance. Who was behind the door wasn't his mother but rather an old-fashion dressed old man. Staring agape at the old man, he watch him smile while he lowered his hat.
"Excuse me young lad, was this the household that had recently purchased the grow up voodoo doll?"
Your little brother recognize what he was referring to and shook his head in agreement.
"Excellent! My name is Merlin, and it just happens that my shop is having a special deal today. With every purchase of a grow up doll, you also get the grow down doll as well, and vice versa." The old man then drew a similar doll in his hand. It looked familiar to the one his brother had, but its limbs were stubbier, and its stature was overall smaller. "Just like the grow up doll, you will need to provide this doll with the hair of the subject, even just a single strand of hair would work. Then reciting the magic words 'Age contra, transformatio' they will begin to regress in age. Of course to stop this transformation, you must say 'processus claudum'. Be careful going too young, you might reach a point of no return." The old man warned looking down at the little boy. "I would advise you not using this doll on yourself young lad, you don't have much years to even give up!" Chuckled the old man. "The grow up doll would better suit someone of your... stature." With that the old man handed your little brother the grow down doll. Waving good bye he proceeded to vanish.
Your brother stared in awe, he didn't really understand what the old man was saying, but he knew he had a doll of his own now. Feeling a bit empowered, he decided to show his 'friends' the new doll he had as well. Waddling up the stairs he slowly made his way down the hall.
"Wow! You two are so BIG now!" He heard an unfamiliar voice hollering from his older brother's room. Peeking inside from the crack of the slightly opened doorway, he couldn't help but gasp at the sight before him. Inside his brother's room were two grown men. One of them was blonde wearing really tight jeans and t-shirt, he had big muscles and a lot of body hair. The other one was a red-headed man wearing really tight tank top and running shorts, he had even bigger muscles and a big bulge as well.
Your little brother recognize these two men as his friends Johnny and Ryan all grown up. He couldn't help but marvel at their adult forms. However, Alan still looked the same as when his brother took them upstairs, the only difference was that he was now wearing an oversized shirt.
"Annos progressum, transformatio" he heard you say, silently repeat the words himself.
He watched with wide eyes as Alan proceeded to stretch taller into the air. Your little brother's mouth gaped watching the boy's arms and legs lengthening like gum.
"I feel... so... Fucking strong!" The growing teen groaned, causing your little brother's body to trembled. To think that tiny Alan would become so big... he had to get his hands on the grow up doll himself! But how could he? A tiny little boy like him was no match against four grown ups.
With that, your little brother watched as his three friends surrounded you, causing you to drop the grow up doll unknowingly. One thing lead to another, as he watched them pushed you down onto the bed. Suddenly the grown men began to undress.
"Why are they getting naked?" Your innocent little brother asked himself as he continued to watch the naked guys pull off your own clothing not to long afterwards. After that, he saw his friend Johnny climbing onto your lap, shaking his fat ass up and down. Having no concept of sex, your brother couldn't quite conceptualize what was transpiring before him. All he knew it was quite humorous watching Johnny's big booty jiggled as he played that weird game.
Johnny huffed while he pushed you into the bed lying flat as his butt jiggled harder. Ryan and Alan stood by Johnny, their backs turned away from the door. Your little brother knew this was his chance to pick up the grow up doll on the ground. Sneaking in, he quickly grabbed the doll, turning around to head back out.
"Ohh.... FUCK!" He heard the blonde man yelped. This cause your little brother to jump, thinking that he had been caught. Turning his little head around, he only saw Johnny clenching his ass cheeks repeatedly as his body shivered. His brother's legs wobbled while his toes curled.
"Grown ups are so weird" your little brother scoffed as he waddled out of the room. Now possessing both dolls, you little brother couldn't wait to try the grow up doll for himself. Looking for someplace a bit more secluded to continue, he made his way inside his parents' room. Looking at the floor, he notices his friends' discarded toddler clothes once again. Standing by a mirror, he transfered the three strands in hair onto the grown down doll. It amazed him that the hair snapped on like magnets. Rustling through his own hair, he finally got a loose strand, as he snapped it onto the grow up doll.
"Annoso progrenum transmato" he slurred. Waiting a while, he notice nothing was happening, "annos... progressum transformatio?"
Suddenly he gasped as his whole body shook. He watched how his little body began to stretch taller before the mirror in front of him.
"It's happening! I-I'm growing, I'm growing up too!" Your brother smiled as he watched his limbs lengthen. His body quickly transformed from a toddler to a kid. His clothes were starting to pinch into his skin.
"Ow... Ouch! My clothes... Uhh... I need to stop for now... What was it... Oh yeah... processus claudum!" he rambled. Your brother gasped as the sensation stopped.
Looking back at the mirror, there wasn't a toddler looking back at him, but a perky preteen in tight clothing. Yanking the tight garments off, your brother stared wide eyes at his new figure. Touching his arms, he can feel some muscles growing, and looking down, his feet was definitely a bit bigger than before. "This is incredible!" He smiled.
Just then he remembered the events that transpired shortly beforehand. His face suddenly contorted in disgust as he realized what Johnny was doing with you with a new sense of clarity. "Oh my God! That is so GROSS! Why would he do something like that... with HIM?!" Your brother couldn't believe why he didn't understand what the two of you were doing on the bed just moments before. He can now clearly recall seeing your schlong enter his anus, causing him to spit out in disgust.
"I can't believe him! Turning my friends into FAGOTS!" Looking at the grow down doll on the ground, he smiled. "I think they all had more than enough fun... but first, I want to finish my own growth." With that he recited the magical words as his body began to tremble once more.
Smiling, he watched his manly assets shoot up before his eyes. His arms and legs' muscles swelled into bodybuilder proportions as his body stretched up. His back widened as his abs and pecs pushed out."Mmm... not bad" he smirked as he flexed his arms, satisfied by their size. Feeling he had grown enough, you brother recited the stopping words and the transformation ended.
Twisting and turning his adult body, your brother was rather proud on how hunk he grew up to be. He once again thought about Johnny riding your cock, although he was still disgusted of it, he was unconsciously rubbing his new manhood. He couldn't help but jack off his new adult cock, relishing in the pleasurable sensation it provided. Squeezing his bull balls in one hand while he stroked his schlong with the other one. Overwhelmed, you brother collapsed onto the nearby bed. His thoughts became stronger as he remembered Johnny shaking his ass harder, and he started to spill precum like a faucet.
"Oh, God!" Your brother huffed as he arched his lower back up. Suddenly, his body quaked as he reached his own first orgasm and shot a big load of cum. Trembling from his intense climax, your brother heard another cry of pleasure coming from the room next door. "I think it's time I paid my friends a visit." He smirked. Lowering his sturdy legs off the bed, you brother opened your father's closet, searching for some clothes to gown on his new bulky figure. Finding a shiny blue speedo, he grinned as it could help him to show off his hot new body.
Heading out, he peeked into your room once more. This time he saw Ryan laying face down on your bed, his fat ass up as you rammed into it repeatedly. Glancing around the room, he saw his friends Johnny and Alan standing not too far away. As he watched Johnny stroking Alan's dick, he was rubbing his own through the speedo's fabric. Looking at his other hand, he had the grow down doll with it's three strands of hair: gold, brown, and orange. Your brother remembered the words the old man had told him and smiled "Age contra, transformatio" he mumbled quietly.
He watched how the guys froze, trembling as their bodies began to regress. However you were woefully ignorant because you were still pumping your dick into the red-head on the bed.
"OooOoOh! Your dick is so BIG!" Ryan's voice vibrated.
Scanning the room, your brother watched as the former adults plummet back into teenager. Their astounding bodies were slimming down as their heights began to inch lower as well. Finally he watched you yank your dick out of his friend. "Looks like he's finally noticing." He grinned as he watch you twist and turn in confusion.
As the boys return to being toddler, ducking under your bed covers. Your brother smiled as he saw you make towards the doorway...
Kicking back to present time.
"Processus claudum."
Your brother laughed as he looked at the little 5-year old boy sitting inside pants too big for him. The little boys on the bed stared with wide eyes and open mouths.
"Look! He's small like us!" Johnny cried out.
Your brother continued to giggle as he looked around the room.
"What to do now?..." He grinned.