So far, Ty had woken up on his birthday and had discovered - through retroactively altering his foster brother Dustin's age, physical development, and entire life history - that he had somehow gained a power to change everyone and everything however he wanted.
Now, Ty had grown himself up, changed Dustin into a small girl, and had made it so that kissing the little girl would grow her up in age. This had resulted in progressing the little 13 year old with a physical body of 10 into a properly sized and developed 13 year old girl with a series of sinful kisses.
Now Ty had the option to continue or stop. But if he continued kissing 'Dusty' as she now was, she'd continue growing up, and he wanted to see what kind of a woman she'd become. Since Ty could do whatever he wanted anyway, since he was free of consequences anyway, he decided to keep going.
* * *
They had decided that Dusty's brown flowerprint dress was far too small for her now that she'd grown so much. Now, Dusty was completely naked and examining herself in front of her body length mirror in the corner of the room. Presently her hands probed her 34a sized breasts, fondling them in childish curiosity. "Ty..." Dusty finally turned to her step brother, sitting on the bed. "I think I do wanna try and get bigger. I want to me the biggest girl in my class!"
"Well, Dusty..." Ty smiled, having anticipated this. "Now that you're not small for your age anymore, I'm not sure that kissing will make you keep growing." Indeed, Ty had just revoked his previous wish to make her age when they kissed.
"Are you sure?" Dusty looked sad and her eyes fell. "I thought you said I'd keep growing if I kissed an older boy!"
"Well, you can try, but I don't know if it'll work now."
Dusty proceeded to approach the end of the bed where Ty was sitting, and like he had taught her, she laid a delicious and passionate kiss on his mouth, teasing his lips sensuously, heightening his arousal. When she drew away, she was clearly disappointed. "Aw, no." Dusty looked herself over. "I'm still the same." She sniffled slightly. "This sucks. I wanted to keep growing."
"Well..." Ty grinned deviously. "There is another way, sis. But it means you have to do something only big girls get to do to big boys."
Dusty's eyes widened and she blushed. "Y-You mean... have sex??" She whispered the last word, horrified.
"No, no." Ty shook his head. "Not sex, sweetheart."
"Oh, good!" Dusty brightened. "Cause that would be gross."
"Yeah!" Ty agreed, then made another wish. "No, sweetie, in order to keep growing up all you have to do is touch an older boy's penis." And he desired that Dusty would be okay with that.
"Oh! Is that all?" Dusty waved her hand like it was nothing. "A couple girls in my class have done that already. Maybe that's how they grow up." She smiled. "Okay! I can touch your penis, Ty! Anything to make me bigger!"
Too easy, Ty smiled. And with that, he unzipped his pants, drew down his underwear, and revealed his rock hard five inches of cock for Dusty. The 13 year old blushed deep red, stared in fascination, and then approached.
She put her fingertip on it at first, but nothing happened. She looked at Ty sadly. "No, no, sweetie." Ty explained. "You have to wrap your hand around it and hold on."
"Oh!" Dusty nodded, then proceeded to clench Ty's shaft in her palm. Still nothing happened.
"Now slide your hand up and down, sweetie. That's called jerking me off." Dusty complied as she was told, carefully pulling Ty's shaft in her hand and watching his reaction as he melted.
"Does it feel good?" Dusty asked innocently. "Is that why boys like this?"
"Yeah..." Ty closed his eyes. "It feels really good, Dusty. Just keep jerking, and you'll start to grow."
Dusty did as she was told, concentrating on jerking Ty's penis like he had taught her. Sure enough, after a minute or so of jerking on him, the 13 year old started to grow again.
"Ty!" Dusty whispered. "It's working!" The two of them stared in amazement as Dusty began to gain more height. From her coltish 4'9" she was sprouting upwards at a slow and steady rate. At the same time, she was getting more feminine. Her little breasts swelled, while her hips expanded. Her legs got longer, her face got older, and her fingers and hands got longer and daintier. In just another couple minutes she was halfway to 14, now 5'1" and much more developed.
"Oh, honey..." Ty gasped. "This is awesome! Keep jerking me and keep growing. You're doing great!"
With a smile, Dusty nodded. "Okay!" She was starting to get aroused as hormones flooded her. Her nipples grew erect, and as she jerked a sweating turned on step brother she kept growing. Her hair grew long and curly, into sinful blonde locks. Her torso elongated, grew more in proportion, her neck stretched, her face lost baby fat, became soft and angular, all the while her hips grew, her ass ballooned, her legs got long and shapely, and her height increased. Her breasts, particularly, were really filling out. They had become gorgeously pert 38B. She was now 5'3" and a nice 14.
"Yes!" Ty stared. "Don't stop, Dusty! Don't stop!"
The girl did as she was told, her bigger hand more easily jerking Ty's cock. It was hard and warm in her hand, and she stared in fascination at how good it felt for Ty. She found herself licking her lips as biological urges assaulted her rapidly aging body. Soon she was 15 - a sexy 15. Tight, cinched, and toned, the girl's body was hard and well shaped, with a pert heart shaped ass, shapely hips, and long sinewy legs. Her breasts had blown up incredibly, now 39c, and her hair hung down her shoulders in gorgeous thick blonde curls. The girl's face had gotten slimmer, sexier, while she had gotten taller. Now she was 5'6" and 15.
"O-Oh God!" Ty tapped her on the shoulder. "Stop, Dusty, stop."
The 15 year old blinked and quickly let go of his penis. "What's wrong, Ty?" She gulped and looked down at herself. "Did I do something wrong?"
Ty simply stared at the sexy 15 year old in awe and blinked. "Wow, Dusty... you're... you're gorgeous."
She looked over herself back and front, stared, and blushed deeply. "I... I did grow up nice, didn't I? I look like a junior high girl! I'm so... pretty." She clutched her boobs and grinned. "And I've got big boobies!"
"Yeah..." Ty stared dreamily. "Now... do... do you want to keep growing?"
The girl leaned on the bed excitedly and smiled, giving Ty a great view of her tight firm tits. "Can I?!" She asked excitedly. "Can we grow me up all the way?"