Ty thought, I need a mate for this body. I think I'm gonna stay this way for a while. He ran to door and realized it was closed. He had two options, he could bark and get someone's attention, or he could wish for it to open. Then he thought, I wish that Dustin would open the door, come in, and not be able to leave.
Not too long after that, Dustin certainly came in, closed the door and wasn't able to leave. Dustin heard a growl behind which backed him into a corner, and he saw a wolf growling up at him.
Then Dustin found himself naked in the corner, and he quickly covered himself up. Next, he found that his body was get covered in layers of fur. He then found what he was covering up was no longer just his penis but was now his sheath as well. He bent down on all fours and soon a tail grew above his now wolfy butt and his hands and feet became paws. His ears moved up and became pointed, his mouth and nose pushed out and became a muzzle and his body became that of an adult male, grey wolf's.
He slumped to the ground and began to whimper as his sheath and balls grew a little bit, but were still small compared to Ty's. Ty decided to make sure that his brother knew EXACTLY who was in charge and made his equipment grow a little, then his whole body. By the time he was done, Dustin was shaking in the corner of the room, shaking and whimpering with fear as he watched his previously younger and smaller foster brother become a monstrous wolf (or rather, a large one. Dustin was actually a bit smaller than most adult wolves)
Ty, feeling a little sorry for his brother, walked over and licked Dustin's muzzle and tweaked the little guy's memories. Soon Dustin was only barely whimpering as his penis slid out of his sheath, his tongue now joining your in a kiss of sorts. You always had a thing for your brother, and now he's in love with you, thinking that he always had been (instead of torturing you), now a wondering, caring submissive (to you anyways) wolf mate, never thinking of betraying you.