It fell to Draco to train Harry's new recruits.
"To cast the Patronus, you must concentrate on your happiest memory. Close your eyes and practise bringing it to mind. I'll measure its strength."
They laughed nervously. Draco picked up an object from his desk and walked along the rows.
"Excellent, Fletcher-Brown. Think a little harder, Jackson." He sat down. "Good. More tomorrow. Dismissed."
He wrote one word -- "Done" -- on parchment and sent it off with his owl. Then Draco smiled and picked up the Pensieve. There was time to watch a few before he poured them down the drain.