Steven groaned as the funny feeling moved to his spine. There was the most bizarre and nearly painful twitching all the way from the start to the end of his back. It was strongest at the very tip of his tailbone, where a pressure was building. A strange little muscle began to twitch around down there, which felt very strange, since Steven had been aware of such a thing before. A thick knot of skin started swelling up from there and started squeezing awkwardly against the back of his pants as it grew. The pressure became worse until he had to lower his trousers a bit in the rear just to release whatever it was. The stretching in his spine picked up speed, and the swelling sensation of his lump grew more intense, until he his eyes caught sight of a dangling flesh-colored object hanging ever lower behind his knees.
"What in the world is that?!" he asked to no one in particular as he reached between his legs. As soon as he grabbed it, his eyes went wide, and he yelped, startled by the shock of grabbing himself in an unrecognizable way. Biting his lip, he tightened his grip, and then had too let go because it felt too weird. He could actually feel a chain of bones in there, far away from his head, as though he had somehow actually managed to wrap a had around his spine. Worrying that he'd mysteriously injured himself in some possibly debilitating way he'd never he'd never heard of, Steven felt a strong spasm in his rear and saw the dangling thing lift up between his legs and point ahead of him. Cautiously, he reached one hand around his side and felt behind him, and sure enough, a long string of flesh and bone was pressed up tight against his bum. Reaching forward with his other hand, he wrapped his palms around the end of the strange appendage and finally found the far end of his spine.
"What is this thing?" he slurred, wrapping both hands around it and exploring it thoroughly, and then it started to itch. Long dark-and-light hairs grew from it within seconds, and then they grew even longer and thicker, so that Steven was left holding a shaggy grey tail in his hands, almost the kind of tail a dog might have--the same kind of animal he'd interpreted from the name in the dice.
"What?! No! That can't be right!"
He tried to pull the animal-like tail away from him, but he couldn't, and it hurt far too much to try. He gave up and simply let go of his tail, which only tucked up even tighter from between his legs. He called the caretakers name as loud as he could.
"Calm down, Rover! I'll bring in your treat in a moment. Just let me get pasta a tiny bit softer, and I'll be right in, alright?" the caretaker answered.
Rover. The caretaker was calling him Rover. Steven now understood why the dice were always right. They made themselves right, with the power to change anything about you. Rover was Steven's name now. And the dog food in the kitchen smelled better than Rover cared to admit.