Professor Slughorn had a club.
Harry had known this since his third year, when the professor had first arrived at the school.
During his third year, Harry often went to Professor Lupin's office for help with magic, and every so often, he saw Professor Slughorn there.
Harry now knew that Professor Slughorn had been brewing Wolfsbane Potion for Lupin.
It was certainly fitting for the school's Potions professor to do that job.
Still, Harry was rather glad that Snape had ended up confined to a bed at St. Mungo's Hospital that year. Otherwise, Lupin certainly would not have had such an easy time of it.
From Sirius, Harry had learned that his father, James Potter, and Sirius had been on extremely bad terms with Snape at school.
So bad that they would fight whenever they met.
Although Lupin's relationship with Snape had not been quite that bad, it had not been much better, either.
After all, a large part of the reason Lupin had suffered less that year was that Professor Slughorn had added some calming ingredients to his Wolfsbane Potion, making it less painful for Lupin to keep himself under control.
Had it been Snape, Harry had no doubt that he possessed the same ability. After all, as the youngest Potions Master, there was absolutely no way Snape could be anything but highly skilled at potion-making.
Whether he would actually have done it, however, was another question.
As far as Harry was concerned, if Snape refrained from adding something to Lupin's potion to make him feel worse, that would have been professional enough of him.
Because he often saw Slughorn at Lupin's office-Harry had at one point suspected that Slughorn went there so often deliberately to see him, though he had no proof.
During that time, Professor Slughorn often