The sight of his sister, boosted to 6'1" by her high heel boots actually turned David on, as the throbbing of his cock could testify, and this led him to try swapping other things with Jamie, basically using her as his guinea pig. After all, he had to practise his powers on someone, family or not, it didn't matter. The siblings' conversation continued, with Jamie chattering on about their parents, about Alicia, about lots of things, and David only half listened. The next thing he focused on was his younger sister's hair, which she had draped over her left shoulder as usual.
Always wanted to try a new style. David smirked to himself, concentrating. Immediately he felt a weird tingling in his scalp and at the same time he watched Jamie's hair begin to recede in length, slowly becoming shorter and shorter until his exact haircut sat on her head. Conversely, David now reached up with one hand in delight and reached around back to take a handful of his new, long hair. He brought it over his shoulder and peered down at it, his cock twitching in his pants.
His smile grew broader when his sister happened to pay him a compliment. "Your hair's looking good bro, nice to see a guy who looks after his hair." She said, while running her own manicured fingers through her shorter hair.
"Uh, thanks, I try." David nodded, licking his lips.
He was already scanning his sisters body, trying to decide what he wanted to swap with her next. Of course he thought about trying out her pussy, but he was getting such a pleasant experience from his erection right now, he decided to wait to make that particular swap. Her boobs on the other hand... David's heart rate increased as his fell upon her B-cup breasts under her light blue tank top. They weren't too big, so David thought they'd be ideal to try on for size.
As Jamie started talking about what Alicia had been up to, David made the swap. He fidgeted in his seat slightly and tried not to react too much as he watched his sister's modest boobs melting away under her top. As Jamie gained her brother's flat chest, a light coating of hair also appeared on it. With his hard-on threatening to cream his pants, David moaned quietly as his sister's tits slowly sprouted on his chest, pushing out his t-shirt. His new nipples immediately hardened and he bit his bottom lip as he enjoyed the experience. He also swapped Jamie's strapless bra over to himself too.
Man this is so awesome! And incredibly turned on David thought, as he reached up to adjust the bra strap a little.