Ron watched, as Hermione's hair took on more body, filling out, and looking healthier and more vibrant. It was getting paler, gaining a hint of golden blonde. Her perfect features refined, her cheekbones becoming sharper. He ignored his own transformation, more fascinated with hers. Hermione's face becoming a mix of Fleur and Hermione, with the best features of both.
"Wow..." his words spoken aloud, he'd only meant to think them. A coy smile from Hermione made him blush. But his words were cut off with a barking cough. The words themselves deeper, and more gravelly, an almost animal growl. He liked that, but part of him felt the need to see his own progress.
His face looked much hairier, a beard and moustache that reminded him of his disguise for breaking into Gringott's. His hair a leonine mane, was thick and full. His nose was looking more prominent, perhaps an illusion from seeing it with all that facial hair.
That hope was extinguished, as his nose darkened, flattening as it turned distinctly black. Reaching up, he found it was pushing forward, his jaw too. A few hairs sprang from the beard, straightening and standing stiffly outwards. His whiskers,... the words triggered a fear. He realised Hermione had tricked him... him and Harry. A moment too late, he blinked, rapidly his eyes watering. As he fought that back, he looked at the progress through canine eyes.
The hands exploring his face were now backed by a thick mat of hair... fur, he corrected himself. Turning them around, he saw his fingers blacken becoming pads as they curled inwards. His nose and mouth projecting unmistakably into a dog's muzzle. An attempted smile revealing transformed teeth... canines.
A look over to Harry saw a similar transformation. The same confusion on his face. Well, as best he could read the expression.