A.N. — Continuing a trend of following along the canon timeline here, building up the Battle of Hogwarts (May 2). Today was Harry's luck potion adventure, but also the apparition testing by this drabble's subject (who I could've sworn was on the character list...).
111. Wilkie Twycross
Everyone knew the three D's of apparition — destination, determination and deliberation — thanks to the teachings of Wilkie Twycross. But the instructor kept a secret, fourth, D to himself: drinking.
He'd mastered apparition even while pleasantly tipsy. And he needed that liquid courage to face a bunch of overeager sixth and seventh years just dying to get their licenses. Keeping them from dying was mentally taxing, and wore his patience thinner than his hairline. His lessons were pared to the essentials, but that mattered little if the students didn't listen. Judging by the number of splinchings, they excelled at ignoring directions.
A.N. 2 — There was an earlier version of this where the fourth D was dislike, and focused on the students badmouthing Wilkie. But that seemed to follow too close to the book's contents.