Without having to accommodate Aisling's "slower progress" at brewing potions, Roy made truly astonishing strides under the dedicated, one-on-one guidance of Potions Master Snape.
The nearly month-long Christmas holiday was neither particularly short nor particularly long, but with Roy devoting himself to it all day, every day, his almost freakish talent for Potions collided with Snape's unparalleled experience to produce some spectacular intellectual sparks.
Over that month, Roy did more than make substantial progress on the prerequisite potion for the Patronus Charm, bringing the already seventy-percent-complete brew close to completion. In his spare time, he also used the ingredients he had grown in the Forbidden Forest to brew all sorts of potions, including a series of counter-curse potions that were Snape's own specialty. These achievements alone forced Snape, however much he disliked Roy, to admit aloud that Roy had gained considerable insight into Potions. At the very least, he was already better than the vast majority of people in the world.
Of course, the results of Roy and Snape's collaborative research did not end there. Roy still needed to make up for the Christmas presents he had failed to deliver on time to all the staff and students at Hogwarts. Just as he had the previous year, he felt that anything money could buy was not special enough as a gift. So he planned to use the Christmas holiday to rush out a batch of potions with unusual effects, giving everyone at Hogwarts a truly unique present.
Of course, leaving readily available manpower unused was not Roy's style. Since this involved potions, he naturally intended to enlist Snape, who was already brewing alongside him every day. Given Snape's personality, however, when he heard that Roy wanted to brew a "unique" potion of his own, he immediately unleashed a vicious stream