[Twinning, Age Progression, Genderswap]

"Sister! Please, please help me become an adult!"

That was what the young green-haired boy had asked his dearest sister. That was what he had asked her so many times before that she had honestly started to lose count. But at the same time, it was that persistence that made it clear that it wasn't just a passing thought. It was a deep, intimate want. Her brother wanted to be older. He wanted to stand alongside her and protect her, just like she had protected him.

Which was why she had been asking so many people around the Halidom to try and assist her. Whether it was those versed in magic, those versed in potion making, even those that were aware of ancient technologies or more in tune with the powers that the Dragons possessed. She asked and she asked, hoping to get a bit of help.

Even Garuda, the Dragon that had antagonized her previously due to the misunderstanding that arose between the three of them, decided to lend a hand. Not that she could do much, but she at least tried to help. That was more than she had expected from such a prideful Dragon.

And ultimately... They managed to find something that could help. Something that could let the boy grow older. Although, there was just one thing that was left on the older sister's mind as she looked at the potion she had managed to acquire.

It was still experimental. There was no telling what kind of adult he would become. But as long as he had a clear image in mind, a clear thought reflecting the adult form that he wanted to achieve, then everything should turn out alright.

She just had to keep his mind focused, and he would finally get what he wanted...

---

"Oh! Garuda! Sister!"

The cheery voice of the young green-haired boy, Lowen, echoed out as he ran over to the unlikely pair, all while clutching his staff tightly with a bright smile on his face. He had been expecting his sister by her lonesome, but the Dragon of Gale that had bonded with him showed up as well. That could only mean one thing. They had managed to find something that he'd need!

"Calm down, kid." Garuda, the towering humanoid Dragon, said as she brushed a hand against her hair. "Your sister worked hard to find this thing. I just gave her a lift here and there." She said, already trying to downplay her part in this entire ordeal. Mostly because she didn't want to admit to the boy's face that she had worked well with her.

The older sister, the pink-haired beauty Louise, giggled a bit as she wrapped her arms around Lowen. "Don't listen to her. It's okay to be excited." She said, petting the boy on the head. Ah, she was just happy that he was alright. Every time that he wandered out with the Prince to try and deal with some sort of terrible incident, she couldn't help but get worried. He was still so young. One false move would lead him to get badly hurt. But this would change from today onward...

"Oh, great, you're back to normal." Garuda scoffed, crossing her arms as she turned away from the pink-haired girl. She really shouldn't have bothered helping. Even if it was to see Lowen's cute smile. She should've just let her flounder around and fail to appease him. That would've driven him back towards her, and then...

A brief blush coated her cheeks as she felt a familiar set of arms wrap their way around her thigh, and a soft and affectionate kiss met that thigh as well. "Thanks, Garuda. I'm glad you helped my Sister out!" Lowen chimed, looking up at the Dragon with nothing but respect and adoration in his eyes. He thought so highly of her, despite what she had subjected him to. She protected people with her Gale, after all. Even if she acted like it wasn't intentional.

"H-Hmph." Garuda huffed, remaining quiet while the two siblings handled the rest of this. For now, she was going to just keep an eye on them. She didn't want that potion to turn out to be a bunch of bogus after all. She had gone through the trouble of ferrying her natural enemy all around the kingdom to try and find it, it was only right that she made sure everything worked out.

Lowen giggled a bit seeing her like this. It was one of the parts that he appreciated about the Dragon. She tried to act like she wasn't true to her feelings, but her actions betrayed that facade each and every time. "Can I become an adult, Sister? Please? Pretty please?"

"In a moment, Lowen." Louise said, as she brought forth the shining potion that she had managed to procure. Something that required not only extensive knowledge of how to handle the ingredients that went into it, but several of the Halidom's greatest minds for that field. "Are you absolutely sure you want to be an adult? Don't you think you need the years you'll be skipping?"

"I don't need them if I can't help you out, Sister!" Lowen replied. He really, really wanted to repay his sister for everything she had done for him over the years. Raising him, protecting him, and even now helping him achieve his most important goal. But because she always treated him like a child, there was no way that he could repay her properly. She'd always try to protect him when he'd try to protect her. This was the only path forward!

Louise pinched the bridge of her nose a bit. The boy's intense need to protect her and repay her was admirable. But it only made her more worried. It was why she wanted him to wait until he grew up. But at the same time, he had proven himself to be so capable as part of the Halidom. It was why she had tried to find this potion. Would she let her pride and her need to protect her brother win out, over the need to reward him for being an exceptional little boy?

Ultimately, it would be wrong for her to withhold the potion any longer. Because she had promised him that she would give it to him. "Okay. But you better do your best, even as an adult. Alright, Lowen?" She said, slowly handing the potion over to the boy. Very slowly. So slowly that she almost didn't actually move, as if her subconscious was stopping her when she actually wanted to reward him.

Thankfully, Lowen had dealt with this part of his Sister before. And thus he reached for the throat of the bottle while holding one hand under the bottom, taking the potion from his Sister once her grip finally let up. "Thanks, Sister. I promise that I'll be just as good at protecting you as you've protected me!" He said, all while looking at the rainbow liquid inside the bottle.

It was very pretty. Almost as pretty as Garuda and Louise. But with none of their respective charm. If this was going to make him an adult... Would he end up as pretty as them? Or would he end up like the Prince and his group? They were adults too, even if they weren't anywhere near as good as the older woman pair. If there was one kind of adult he'd like to become, it'd be like them. Specifically his older Sister, but if he ended up as beautiful as Garuda, he wouldn't mind that.

Louise smiled as she watched her brother look at the potion. It was making her worries flare up a little, but it was also exciting to see him take charge. And yet, it felt like she was forgetting something. Something important. Like she had been told before she got the potion in the first place...

Her eyes widened. That's right. She needed to make sure that he was thinking of his own adult self. Not of anything else. "Wait, Lowen-" But by the time she cried out, it was already too late. The boy had put his lips against the potion, and downed the whole thing in what felt like a few seconds...

Lowen let out a satisfied sigh as he finished the potion, tilting his head ever so slightly as he looked at his Sister. Why was she so worried? It's not like the potion was going to do anything bad to him. It was just going to make him an adult that was as good at protecting people as she was.

Just as the thought of Louise entered his mind, the potion took effect. And the boy immediately felt like his body was trying to twist itself around, causing him to stagger back as he dropped the bottle harmlessly on the grass below, panting as his skin started to redden.

"Lowen!" Louise cried out, her worries peaking as she very nearly grabbed him right then and there to try and make him throw up the potion. Anything to stop whatever it was doing to him. She knew it was dangerous. And yet she had gone ahead and given him that potion. Knowing that she was about to put him into danger. She should-

Before she had a chance to get closer to him, she felt something grabbing her arm. And upon looking back, the stern yet equally worried face of Garuda looked down at her. "Hold on just a moment. They wouldn't make a potion that would kill anybody." For once, the Dragon was straight to the point. This was why she had stuck around. To make sure things didn't go wrong. And if there was anybody that could help hm out, it would probably be her.

Louise didn't like hearing it. But it wasn't wrong. She just hoped that her brother would be alright. Even as he staggered around. Even as he grew bigger. Even as his... his hair turned pink... Wait. Oh. Oh no. Was that what the potion was doing..?

Lowen gasped and panted as he felt his body trembling with every breath he drew. It was so weird. It was like some sort of heat had been turned on inside him. Like there was a bonfire lit inside him, keeping him way warmer than he should be. And that warmth was helping him swell, helping him grow. As if he was a living oven that was busy baking his body until it was properly adult...

And while this was going on, the mental image of his sister only sunk deeper and deeper into his subconscious. He wanted to be just like her. He wanted to be as strong as her. As gentle as her. As protective as her. And the potion was going to help with that. He was sure of it.

He just didn't realize that his desire to become like her was helping the potion change him. Even now, as he had started to grow taller, to the point where he was almost the same size as her, he didn't realize that his body had already grown nice and delicate like hers. His hands felt empty without a bow or without a hand like his held in hers...

Lowen let out a brief gasp as the potion kicked it up a notch, and his clothes started to be affected by it as well. His blue robes that had done their best to cover him whenver he got cold from the powerful winds turned into the same kind of dress that his sister wore. A white dress with a green inner side, one that complimented his now exposed thighs and his rather visible chest. Not that he had anything to fill that area out. He was still flat chested.

At least, he was. But he wanted to be just like her. Which meant that within seconds of realizing that he was rather flat and didn't fill out his sister's dress, a pair of beasts that were just as big as his Sister's started to pop out from his chest, resulting in the fabric doing its best to keep any naughty bits from slipping out. All while his panting and gasping turned into outright moaning, the potion making the entire process of 'growing up' a bit more pleasurable than it really should be...

By the time that the heat inside him finally stopped, Lowen could feel the sweat running down his body. He felt a bit dizzy. Like his entire world had been turned upside down. But he was an adult now, right? He certainly did feel stronger. He felt like he could protect people. So why was it that things felt ever so slightly off?

"Sister..?" He asked, only for his eyes to widen. Hold on. That wasn't his voice. His wasn't this mature... Well, it made sense that it was going to be mature. But it was also very feminine. And he was definitely a boy. He thought he was going to end up a Man by the end, not...

Lowen looked to both of the two women that had influenced him. The two that he held so dear. And he staggered towards them, still not used to his new body. It felt like he was walking on heels, and if the worst had come to pass, then-

"Lowen!" "Oi, Kid!"

He tripped. But both of them were ready catch him. And while they were able to stop him from colliding with the ground, they weren't able to stop his breasts from bouncing, which made everything finally sink in. And the reality of the situation hit the boy like a freight train.

Lowen hadn't turned into an adult. Or, well, he had. But he didn't look like what he would look like in the future. He looked like his Sister. Because that's what he had actually become. He had turned into his dearest Sister, Louise. That was why she felt like she was walking on heels. That's why she felt powerful. And that's why she wanted her old hand to cup her own. Because she wanted her older self to be in her life...

"Lowen..." Louise muttered as she looked at the girl that had once been her brother. Now, they were practically identical twins. Oh, she should've warned him. But what could she do now? All that came to mind was a simple hug, pulling the newly converted girl into her arms as she gave her all the comfort that she needed.

The former boy blushed as she looked up at the green-haired Dragon, then at her Sister, then back again. "I'm sorry, Sister, Garuda... I just wanted to be an adult... I just wanted to protect you two, like you protected me..." She admitted. Even though they both knew that very well. They knew that she wanted nothing more than to protect them for everything they had done for him.

Garuda sighed as she ruffled her own hair. This was exactly what she had been worried about. Well, it could've been worse. He could've completely turned into a twin of that pink girl. Then she would've really had to deal with a headache. But at least underneath that detestable layer was the same boy that she had grown to care about. "It's alright, kid. We didn't warn you, not your fault for something we should've done."

"Garuda's right." Louise said, pulling away ever slighlty as she brushed away the tiniest tear that had started to roll down her new sister's cheek. "I should've told you to picture yourself. But I guess you really, really wanted to be like me, huh?" She said, smiling a little bit. Honestly, that thought was enough to make her smile from ear to ear. To think that her precious little brother would go this far to be like her. It wasn't really what she had wanted, but she could make the best of something like this.

Lowen blushed as both showed mercy towards her. She hadn't messed up? Even though her Sister had very clearly warned her about the dangers of the potion? Then... M-Maybe she just had to live with what had happened. But, if that was the case, then...

"U-Uhm. Sister? Do you have my clothes in your size..?" Lowen asked as she pulled a bit further away from her older Sister. "I don't want to look like you if it ends up making you uncomfortable or anything. I know Garuda doesn't really like you either, and..."

Garuda snickered a bit as Louise's face slowly framed itself in shadow. The former boy had said something she really shouldn't have, as the older Sister slowly loomed over her despite the fact they were the same height. Even now when she had become an adult, Lowen wasn't safe from punishments.

"I think it'd be better if we match, Lowen. Besides, you want to prove that you can be an adult that's as great as me, right? That means you have to try and be me first, that's how it goes." She chimed, her voice taking a dissonantly sincere tone as she grabbed her younger Sister by the wrist, dragging her off in the process. Oh, she was going to make sure that they matched. And Lowen wouldn't be able to change that.

Lowen gasped a bit as she was dragged along, looking back to Garuda. "S-Sorry, Garuda! I-I'll be back, don't worry!" She cried out before she vanished into the distance, Louise's pace having tripled as her younger Sister tried to show concern towards the Dragon.

Garuda just waved goodbye to the former boy, before biting her lip a little. Now that she knew the potion wasn't going to hurt that much as long as the drinker had the right thing in mind, a little idea sprung up inside her head. One that involved the former boy, and another dose of that potion.

After all, Lowen would look much cuter if she took after her, rather than her thorn of a sister.