During her first visit at Weasleys' Wizard Wheezes, Hermione encounters her bad conscience. Characters belong to Rowling.
"Phew," Hermione said in relief to Ginny as she applied the thick, yellow paste to the bruise in her face. "It seems to work. Just imagine if I had to go back to school with a big panda-mark around my eye."
"I can imagine," a voice said from just behind her. A startled Hermione turned around, and stood face to face with a girl of her own age. Neither the scarf, nor the thick layers of makeup she had applied, did completely manage to obscure the bright, red pimples that covered her face.
"Marietta!" Hermione gasped. "What are you doing here?" The girl shrugged.
"I was just browsing through the WonderWitch cosmetic charms," she said. "Guaranteed Ten-Second Pimple Vanisher. Excellent on everything from boils to blackheads, they say, but it doesn't seem to work very well on these..." Her gaze flickered to the unlabeled tube in the hands of the momentarily speechless Hermione.
"You wouldn't let me have some of that, would you?" she asked, with just the slightest waver in her voice.