“Oh, I've been underground,” said Lupin.

“Oh, I've been underground,” said Lupin. “Almost literally. That's why I haven't been able to write, Harry; sending letters to you would have been something of a

give-away.”

“What do you mean?”

“I've been living among my fellows, my equals,” said Lupin. “Werewolves,” he added, at Harry's look of incomprehension. “Nearly all of them are on Voldemort's

side. Dumbledore wanted a spy and here I was... ready-made.”

He sounded a little bitter, and perhaps realized it, for he smiled more warmly as he went on, “I am not complaining; it is necessary work and who can do it better than

I? However, it has been difficult gaining their trust. I bear the unmistakable signs of having tried to live among wizards, you see, whereas they have shunned normal

society and live on the margins, stealing—and sometimes killing—to eat.”

“How come they like Voldemort?”

“They think that, under his rule, they will have a better life,” said Lupin. “And it is hard to argue with Greyback out there...”

“Who's Greyback?”

“You haven't heard of him?” Lupin's hands closed convulsively in his lap. “Fenrir Greyback is, perhaps, the most savage werewolf alive today. He regards it as his

mission in life to bite and to contaminate as many people as possible; he wants to create enough werewolves to overcome the wizards. Voldemort has promised him prey in

return for his services. Greyback specializes in children... bite them young, he says, and raise them away from their parents, raise them to hate normal wizards.

Voldemort has threatened to unleash him upon people's sons and daughters; it is a threat that usually produces good results.”

Lupin paused and then said, “It was Greyback who bit me.”

“What?” said Harry, astonished. “When—when you were a kid, you mean?”

“Yes. My father had offended him. I did not know, for a very long time, the identity of the werewolf who had attacked me; I even felt pity for him, thinking that he

had had no control, knowing by then how it felt to transform. But Greyback is not like that. At the full moon, he positions himself close to victims, ensuring that he

is near enough to strike. He plans it all. And this is the man Voldemort is using to marshal the werewolves. I cannot pretend that my particular brand of reasoned

argument is making much headway against Greyback's insistence that we werewolves deserve blood, that we ought to revenge ourselves on normal people.”

“But you are normal!” said Harry fiercely. “You've just got a—a problem—”

Lupin burst out laughing.

“Sometimes you remind me a lot of James. He called it my ‘furry little problem’ in company. Many people were under the impression that I owned a badly behaved

rabbit.”

He accepted a glass of eggnog from Mr. Weasley with a word of thanks, looking slightly more cheerful. Harry, meanwhile, felt a rush of excitement: this last mention of

his father had reminded him that there was something he had been looking forward to asking Lupin.

“Have you ever heard of someone called the Half-Blood Prince?”

“The Half-Blood what?”

“Prince,” said Harry, watching him closely for signs of recognition.

“There are no Wizarding princes,” said Lupin, now smiling. “Is this a title you're thinking of adopting? I should have thought being the ‘Chosen One’ would be