...Dustin!
The transformation must have taken longer than Ty had thought and Dustin had finished his shower. he was probably going to chew Ty out again for what he had done although he still had no proof that Ty had done it.
"Alright, squirt I want you to undo whatever it was you did to me right now, I don't care how you did it I just want it..." Dustin said as he entered the room in his towel, still drying from the shower. he stopped as he noticed that his "squirt" of a foster brother wasn't much of one anymore. He stared for a few seconds at Ty's chest and then his eyes moved down to linger on his much larger cock. His mouth dropped open for a moment as he couldn't find anything to say he was so thrown by the changes. After he regained his senses his expression turned to that of rage.
"I knew it was you, when mom and dad find out about this they are going to have you sent somewhere to be dissected like the freak you are." He turned to leave and Ty jumped up from the bed and grabbed his foster brother's wrist. He yanked him into the room and shut the door, he wished he had a lock but that privilege was only held by his brother, his foster parents insisted that they be able to check in on him at all times. Turning quickly he saw that Dustin hadn't recovered from being pulled so hard, and he was also having a hard time believing that he had just been majorly overpowered by Ty. Ty took the chance to give his brother an offer.
"if you don't tell Mark or June, I'll turn you back to normal. If you try to tell them the last thing i do before i leave will be to turn you into a girl." Ty advanced on Dustin as he said this and with Dustin on his knees Ty towered over him. Dustin quickly held up his hands in a gesture of defeat, although after realizing what he was doing turned the motion into that of him crossing his arms,
"Fine, but if you ever change me again I'll tell them so fast you won't have a chance to try." He said with a scowl on his face.
Ty nodded and sat on his bed, he concentrated like he had when he had made himself bigger and using all the times that he had scoped his foster brother wishing that he wasn't a late bloomer, he returned Dustin to as close as he was before as he could. Dustin grew a few inches and Ty could see the hair begin to grow back in his pits and legs. His cock grew back to about average and Dustin flinched a little as the growth happened almost like it felt good, his pubes filled in again and as far as anyone could tell Dustin was back to normal.
"Good, I won't tell them but don't forget what I said." Dustin said as he made the move to leave.
Well even though Dustin knew that it had been him, at least Ty wouldn't get shipped off to somewhere to be opened up and examined. As he watched his foster brother leave a thought occurred to him, what might Dustin be willing to do to be a bit bigger than before?