Percy and Cho
Percy paused at the sound of the voice and looked toward the speaker. He recognized her immediately - Cho Chang. She'd been Cedric Diggory's object of rescue at the Second Task of the Triwizard Tournament, which was the task he remembered most. Seeing her face reminded him of searching the water desperately for his youngest brother's face, only to have her rescued instead, as well as Hermione.
It hadn't been the first nor the last time he'd feared losing one of his siblings, but he quickly pushed the thoughts from his mind. This was a gala, a time for amusement, not for lingering on the past that he couldn't change, even if he had a time-turner.
Not that the thought hadn't crossed his mind.
"Quite, thank you," he replied with a polite nod. "Are you working this evening?"