When third year starts, Harry already knows that R.J. Lupin was friends with his parents, but is a little standoffish because he doesn’t understand why Lupin never checked in on him. Hermione figures out that he is a werewolf and shares that discovery with Harry; this leads to a conversation where Lupin confirms that the reason he didn’t contact Harry as a child was his lycanthropy, which finally resolves some of their mistrust.