Laughing at Percy

In a moment, they had fallen sideways through the solid metal onto platform nine and three-quarters and looked up to see the Hogwarts Express, a scarlet steam engine, puffing smoke over a platform packed with witches and wizards seeing their children onto the train.
Percy and Ginny suddenly appeared behind Harry. They were panting and had apparently taken the barrier at a run.
"Ah, there's Penelope!" said Percy, smoothing his hair and going pink again. Ginny caught Harry's eye, and they both turned away to hide their laughter as Percy strode over to a girl with long, curly hair, walking with his chest thrown out so that she couldn't miss his shiny badge.
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Harry Potter and the Prisoner of Azkaban Chapter Five: The Dementor