January faded imperceptibly into February, with no change in the bitterly cold weather. The match against Ravenclaw was drawing nearer and nearer, but Harry still hadn’t ordered a new broom. He was now asking Professor McGonagall for news of the Firebolt after every Transfiguration lesson, Ron standing hopefully at his shoulder, Hermione rushing past with her face averted.

“No, Potter, you can’t have it back yet,” Professor McGonagall told him the twelfth time this happened, before he’d even opened his mouth. “We’ve checked for most of the usual curses, but Professor Flitwick believes the broom might be carrying a Hurling Hex. I shall tell you once we’ve finished checking it. Now, please stop badgering me.”

To make matters even worse, Harry’s anti-dementor lessons were not going nearly as well as he had hoped. Several sessions on, he was able to produce an indistinct, silvery shadow every time the boggart-dementor approached him, but his Patronus was too feeble to drive the dementor away. All it did was hover, like a semi-transparent cloud, draining Harry of energy as he fought to keep it there. Harry felt angry with himself, guilty about his secret desire to hear his parents’ voices again.

“You’re expecting too much of yourself,” said Professor Lupin sternly in their fourth week of practice. “For a thirteen-year-old wizard, even an indistinct Patronus is a huge achievement. You aren’t passing out anymore, are you?”

“I thought a Patronus would—charge the dementors down or something,” said Harry dispiritedly. “Make them disappear—”

“The true Patronus does do that,” said Lupin. “But you’ve achieved a great deal in a very short space of time. If the dementors put in an appearance at your next Quidditch match, you will be able to keep them at bay long enough to get back to the ground.”

“You said it’s harder if there are loads of them,” said Harry.

“I have complete confidence in you,” said Lupin, smiling. “Here—you’ve earned a drink—something from the Three Broomsticks. You won’t have tried it before—”

He pulled two bottles out of his briefcase.

“Butterbeer!” said Harry, without thinking. “Yeah, I like that stuff!”

Lupin raised an eyebrow.

“Oh—Ron and Hermione brought me some back from Hogsmeade,” Harry lied quickly.

“I see,” said Lupin, though he still looked slightly suspicious. “Well—let’s drink to a Gryffindor victory against Ravenclaw! Not that I’m supposed to take sides, as a teacher . . . ,” he added hastily.

They drank the butterbeer in silence, until Harry voiced something he’d been wondering for a while.

“What’s under a dementor’s hood?”

Professor Lupin lowered his bottle thoughtfully.

“Hmmm . . . well, the only people who really know are in no condition to tell us. You see, the dementor lowers its hood only to use its last and worst weapon.”

“What’s that?”