Tim guided Ben to your room, or it would be more appropriate to say that it was now his room. The two entered the room as you sneaked behind the door, observing Tim’s next move.
Ben looked around the room and saw a small pair of rain boots, dog rain boots. "You guys had a dog? Never knew that." Said Ben.
But much to his luck, this gave Tim the perfect idea. "Oh, yeah… we had a dog named Spark, but he ran away years ago." He said. "Bet your small feet can fit in his boots."
Tim’s manipulation of Ben was already yielding fruit. "Well, let's find out!" said Ben as he forced his feet into the miniature, yellow rain boots and began to feel a tingle all over his body.
"I'm… feeling funny."
Tim was unable to hide his smile of mischief and took a step back to observe the changes.
Ben’s body hair grew into fur that covered more of his body by the second and changed colour from brown to white.
"Wh— What's going, Will? Why are you laughing?" He asked Tim nervously.
After that, his hands reshaped themselves into paws, as claws began growing, and then a tail forced its way out of his jeans as it wiggled, and his clothes became loose and fell off his transforming body.
The changes moved to his noggin as a muzzle pushed itself out, remoulding his face and repositing his ears which herald the growth of more fur. "You did this, Will, didn't you?"
It brought Tim a great pleasure to be called by your name as you were helplessly gaping from behind the room’s door, in Tim’s body.
The changes came to an end as Ben fell on all four paws, and spoke his last human words. "This is all your fault, Will, you piece of sh—WOOF!"
Tim cackled with laughter at Ben, now a white golden retriever. But you were terrified by your brother’s display of cruelty, especially towards Ben.
"Go on now, *Spark*." Commanded Tim while humiliatingly emphasising his new name.
Ben couldn't spare any more of your brother’s experimentations, so he leaves the room and is confronted by you.
"I know you're not Spark —He's been playing with us like toys, and we need to stop his experiment before he hurts somebody." You tell him.
Ben could only react with a loud "Woof!", but oddly enough, you could understand him to a certain degree if only for the human mind’s effort to communicate with you.
"I wish I could explain more to you, but I'm not Tim. I'm Will."
Ben could only stare at you in bewilderment and confusion, but before you could say anything, Tim comes back and says: "I'm not done yet with you two. I have two pair of shoes we borrowed from the Erickson twins, and you two better wear them."
The Erickson twins were Tim’s best friends before they moved to another state when they were eight, and it's clear that his experiments were far from over.
Both you and Ben stare at each other, thinking of a way out.