Greta loved her brother Tommy, very much, but she always wanted a sister, and she realized if she didn’t do something soon, she would never have one growing up. She asked Tommy if he would help her be happy, without telling him what it was she needed him to do. He agreed to help her with out being inquisitive about it.
Much to his surprise, after she muttered a spell from a book, he was now a SHE! He looked over his body in shocked amazement, the hair, boobs, and new crotch all catching his attention first, the later the smaller frame, soft skin, large hips and bottom, and small hands and feet. He looked in a mirror stunned, then spoke for the first time in his new voice, astonished that he sounded like he should for his appearance, like a young lady!
Tommy asked her if this is what would help her, him being a young lady, and she said yes, she wanted a sister, she wanted to spend the rest of her days growing up, with a sister, and since he was such wonderful brother, he would make the perfect sister, with a few changes of course! Tommy being a good guy, and now even a good girl, shocked as he was, gave in to his sister, hugging her, but surprised how weird it felt having both their boobs touching when they hugged.
Greta made the spell permanent, even though Tommy was a little squeamish, but soon they both became even closer as two loving young ladies and sisters with each other.