To set the scene: Julie, currently 10 years old and her brother Nick, 13, have never gotten along. The issue being that Nick seems to refuse to grow up while his sister is quite mature for her age. The pranks and jokes he finds hilarious simply bore and annoy her. Perhaps the two would have grown out of their conflicting personalities with time. But that wouldn’t be any fun, ay? So what if instead. The two got what they deserved. Nick, refusing to grow up and Julie already doing so. 

At this point in time Nick is about to begin 7th grade. He stands 5’3, slightly tall for his age and if his 6’4 father is anything to go by, would have grown into quite an imposing man. He is regarded as quite smart as well, when he applies himself, and is always picked first for sports teams.

Julie is in the 4th grade, at 4’7 inches tall she is also slightly big for her age. Her grades at this point are better than Nick’s were in 4th grade, likely because she actually takes school seriously. 

What our heroes don’t know is that at this point things have changed. Nick will remain exactly as he is both in terms of physical and mental development. While Julie will reap the benefits from whatever growth would have gone to Nick. it may take some time for the changes to become noticeable but change they will. 

1 Year later

Nick is frustrated. Over the course of the school year he watched his male classmates go from slightly shorter than him to around the same height or even taller. His mother assures him that he’s just a late bloomer and he’ll catch up soon. His grades have suffered as well and while he’s managed to move on to the 8th grade, things are only going to get harder.  

Julie on the other hand has had a great year. She grew an astonishing 5 inches to 5 foot even and did so well in class that she got bumped up to 6th grade for the following year. Both she and Nick were surprised when one day they came face to face while she was wearing soccer cleats and he was barefoot. In her shoes Julie was the same height as her older brother. 

That summer the two didn’t see much of each other. Julie was busy playing on various sports teams while Nick mostly hung out with his friends around the local neighborhood. Come the start of the school year things had changed even more. 

Nick, of course, was the same but Julie had grown an additional 3 inches, as well as packing on a fair amount of muscle. Nick pretended not to notice but when they were taken shopping for back to school clothes it couldn’t be avoided. Nick was shocked to find that his younger sister needed larger shoes than him. As she tried on the pair he subconsciously stood behind her only to find that he needed to look up at the back of her head while barefoot. When Julie turned around and noticed that she was looking down at her older brother she smiled and ruffled his hair with her hand. Nick would always be sure to be wearing shoes around Julie after that. 

During the school year Nick did his best to avoid his rapidly growing little sister. This was helped by the fact that they went to different schools and both left home and school at different times. Even while home he would spend most of his time either in his room or at a friend's house. Of course this didn’t protect him from his growing classmates. By that spring most of his male peers were between 3 to 6 inches taller than he was while the girls were about the same height, though some were quite a bit taller. He was finding his classwork almost impossible as well and in a very embarrassing student teacher conference was told he’d need to repeat the 8th grade. 

As you can expect Julie’s year was the opposite of Nicks. She grew 4 inches in total putting her at 5’7, well above the average height of even adult women and she was only 12. Not that you’d think that. Along with growing taller Julie’s features had matured as well giving her the look of a 14 or 15 year old girl. Her budding C cups further enhanced this effect. She was finding 7th grade to be a total breeze, despite being a year ahead of her age group. Unfortunately she was told that she couldn’t skip directly into highschool as there were some 8th grade classes that she needed to take. Even so, she got a kick out of the idea that next fall she would be in the same grade as her big brother. 

Shortly before the end of the school year Nick and Julie’s parents decided to go on a weekend getaway for their anniversary. The two simply couldn’t find a babysitter, most older kids were focusing on finals, so instead they made a controversial decision. They left Julie in charge. 

Now remember that Nick has been avoiding his litter sister for nearly 8 months as best he can. But when he and Julie were called downstairs to wish their parents goodbye he couldn’t avoid her. As he came down the stairs he saw Julie standing in the hallway leading to the front door. As he reached the final few steps he looked on in horror as the back of her head rose higher and higher. His eyes fell on the back of her neck. He gulped and tore his eyes away from his towering sister to stand next to her and say goodbye to his parents. 

It was here that they dropped the bomb that Julie would be in charge of her older brother for the weekend. Nick protested of course but it was all in vain. As his parents drove off he looked up at Julie who smiled down at him, her eyes a mix of joy and second hand embarrassment. 

The weekend wasn’t nearly as bad as it could have been. Julie was a fair and just mistress and largely left Nick alone. Apart from preparing meals and making sure he went to bed at 9pm. She did give him a small heart attack by trying on a pair of her mom’s heels. They were only 4 inches, bringing her up to 5’11, but the sight of her brother’s head fitting comfortably below her chin was just too funny to her. 

Nick found it very difficult to avoid Julie over the summer. His friends seemed less and less interested in hanging out and she was spending a great deal of time at home studying. She said she wanted to be fully prepared for the school year. Initially Nick halfheartedly joined her, at the request of his mom, but quickly gave up once he realized that he simply couldn’t keep up. 

Previously Julie left for school early and took the bus, with Nick getting a ride from his mother on her way to work about half an hour later. This year they were in the same school. It must be noted that juli has grown even more over the summer to an amazonian 5’10 in bare feet and near 6 in her shoes. As the two walked out the car Nick went for his usual front seat, only to feel a hand on his shoulder. 

“Front’s mine shorty. My legs are waaaay longer than yours and need more space.” Nick tried to argue but their mom shut him down.

“Just give your big sister the front so we can go or we’re gonna be late.” The act of calling Julie his “Big sister” completely shut down any protest Nick could’ve put forward and he relented.

That whole school year was a nightmare for Nick. Not only did Jule seem to grow taller and more mature every day but she quickly left him in the dust as far as grades were concerned. People around the school started calling Julie his big sister as well calling him “lil’ Nicky”. A fair observation as He was now shorter than a majority of his female classmates. Julie, on the other hand, grew rapidly and by the end of the year she stood at 6’3 tall at only 13 years old. She looked more like a highschooler though and her massive D cup breasts got her plenty of attention.

Both she and Nick’s final student teacher conferences were scheduled at the same time and for simplicity's sake took place in the same room. Julie came dressed in a stylish and mature long skirt and blouse while Nick wore his favorite basketball shorts and T. The contrast was so immense that the teacher initially thought Julie was Nick’s mother. Once the confusion was cleared up they got down to the meat of the discussion. There were really only two things on the docket. Firstly they congratulated Julie on her outstanding performance and offered to let her skip Freshman year all together and move straight to her Sophomore year of highschool (10th grade). As for Nick they regrettably informed him that not only did he not pass the 8th grade but they were actually going to have him repeat the 7th. Hearing while in the same room as his taller, stronger and now undeniably smarter younger sister was one hell of a blow to Nick’s already withered pride.       

That summer Nick spent most of his time in his room. Julie had finally found a balance between sports and academics and spent all her time either on the field or in the local library. Now 14 she had continued to grow exponentially and stood 6’8 tall. She decided to try and have a talk with her little brother, as she suspected that as things were he may not go to school at all. So one day after soccer practice, still wearing her tight fitting, grass stained uniform and cleats, she knocked on his door. 

“Nick? Can we talk?”

“No.” Was the only response. 

“Come on, let me in.” Julie turned to handle and found that it wasn’t actually locked. As she slowly slid the door open she heard Nick run across the room and felt a light “thud” as he pressed himself against the door, trying to force it shut. 

“Go away Julie!” She just sighed. 

“Nick, honestly. Do you really think you can stop me?” She made her point by unceremoniously throwing the door open with arm, sending Nick stumbling backwards. She stepped into the room, actually having to duck slightly as her cleats added several inches to her height. She placed her hands on her wide hips and looked down at her older brother. Nick got mad. He threw himself at Julie and tried to force her backwards. Unfortunately for him he overestimated the distance between himself and her rock hard, and exposed, abs. His face collided with Julie’s ribbed stomach and he fell backwards, clutching his bleeding nose. He sat on his floor stunned. Julie quickly leaned over, picked her brother up and brought him to the bathroom. Placing him on the counter she tenderly cared for his bloody face.  

“That was just silly, little man.” Nick offered no response so Julie continued. “I think it’s time we had a talk.”

“About what.” Nick mumbled.

“About coming to terms with our relationship.” 

“What do you mean?” 

“Well it’s clear that the idea that your little sister is both so much taller than you and smarter than you is causing you grief. And for my part it’s pretty embarrassing when I have to tell people that my “big brother” is 3 grades behind me and barely reaches my breasts.” Nick remained silent. “So, I think I have a solution.” Julie stated as she wiped the last of the blood from Nick’s face. 

“And what’s that?” Nick offered scornfully. 

“From now on. I’m your big sister. Not just ‘big’ but elder as well. And you’re my little, younger brother.” She beamed down at him.

“W-what? That’s not how this works. I'm 17 and you’re 14!” 

“Do I look 14 to you?” Julie stepped back and gave Nick a full view of her womanly body. No she didn't; she looked closer to 18 or maybe even 20. “And you, you still look like a middle schooler.” 

“Yeah so what! We can’t just pretend you’re older than me.” 

“Actually, we can! Mom’s pulling some connections at the county clerk's office and they’re gonna change our birth certificates. As of today I am 18 years old and you are 12. I’m even getting my drivers license next week!”

“Is that even legal?” Nick asked, mouth agape. 

“Well technically, no but it's the only thing that makes sense. I think things will get better for you if you just accept the fact that I’m your older sister and you’re my cute little brother!” 

“Why do I have to be even younger than you actually are though?”

“Because that’s how you look and behave. Now. No more complaining. You are going to start studying up and I’m going to help you. We’ll get you into highschool yet!”

This new strategum paid off. Once Nick got over the embarrassment of having his little sister drive him to and from school and started actually referring to Julie as his big sister, things got easier. Of course there were still problems. It took Nick nearly 3 years to finally make it into 9th grade. Julie graduated highschool 2 years before and at a monolithic height of 7’2. She would go on to attend Harvard University under multiple sports and academic scholarships. Within the next 4 years she not only won 5 gold medals in the olympics but also managed to squeeze out 3 Ph.Ds. Now 24, although actually only 20, she started a career as the head of her own startup, making her first billion dollars just a year later. Nick, now 18, though actually 23, dropped out of highschool and spent some time living with his parents. Fearing that this lifestyle might lead him down the wrong path, Julie offered to let him move in with her, under the condition that he go back to school. He accepted. And later that year, after a couple  more “edits” to their identities he rejoined the world as her 12 year old son. Julie was now “32” as far as the government was concerned, having given birth to Nick when she was 20. While their parents were initially skeptical of this idea, a few million dollars to look the other way smoothing things over nicely. 

It took Nick some time to get used to calling his once little sister “Mom” or “Mummy” as he eventually settled on. Julie took to being a mother far more easily. And only a year later introduced Nick to his “new” little sister. A girl named Cherry. Cherry was born from a one night stand that Julie was determined to keep. Nick and Cherry got along well from the start but soon things changed again. By the time Cherry was 13 she was taller than Nick. And Nick, who had never managed to complete school, found himself once again unable to keep up with his little sister’s rapidly growing intellect. 

“You’re my big brother aren’t you? Well, older at least,” She giggled girlishly. “ Why do you need my help for your homework? What grade are you even in? Shouldn’t you be in highschool by now?”

“6th grade….” Nick offred quietly. 

“SIXTH? You mean you’re two grades behind me? How is that even possible?”

“Mom said this would be the last year….” 

“Last year of what?” 

“That I’d have to go to school. And that after this year, you’d be my older sister.” Cherry stood in front of Nick, her eyes easily looking down at the top of his head. The 13 year old girl towering over the 37 year old man, though he really did look like a 12 year old boy.

“I suppose that’s for the best then. Mom did always say I’d eventually outgrow you in more ways than one. Fine. I’ll help you, it’s kinda neat being so much smarter than my big brother!” 

“You have no idea….” Nick sighed.