Something was happening. There was change in the air, and trepidation as well. The professors seemed tired and pale and curiously absent-minded in class, and Professor Flitwick was so flustered that he accidentally set his handkerchief on fire when attempting to do demonstrate a cleaning charm.

The Defense Against the Dark Arts teacher, a normally cheerful little witch named Professor Merrythought, entered class with a new grim and efficient demeanor and attempted to teach the students to produce patronuses. "You never know when you may need them," she said briefly by way of explanation.

The lesson proved to be extremely difficult for most of the class, and the majority of the Gryffindor students only managed to produce wisps of silvery vapor after an hour or so of strenuous concentration. Algie's silver cloud had four little protrusions, and Harry suspected that they would eventually develop into the legs of a toad. Algie, although eerily similar to Neville, seemed to have a merry confidence about him that his future nephew did not. Maybe because Algie's parents weren't tortured to insanity by the death eaters…

Harry's own stag patronus made the other students gasp as it cantered around the room. "Oh, excellent!" cried Professor Merrythought, beaming at him. "Where on earth did you learn to do this? Home-schooled, you say? Goodness gracious!"

Harry looked over at Minerva, expecting to see a silver cat shoot out of her wand, but there was nothing feline about the small blob emanating from her wand. "How do you do it?" she whispered to Harry. "I'm thinking good thoughts, but it doesn't seem to work properly." She seemed quite upset with herself, and Harry felt bad for her.

"What are you thinking about? Perhaps you need to draw on a stronger memory."

Minerva frowned. "I'm thinking of my parents, my dear mama and papa. What could be happier than that?"

Harry smiled at her. "How about the first time you played Quidditch?"

"Really?" She sounded quite surprised at the suggestion. "I thought – I thought it had to be something about others for some reason, not just something about me."

Good God, how are they raising girls in 1942?

Harry shrugged. "But playing Quidditch makes you happy, doesn't it?"

Minerva looked doubtful, but when a graceful cat leaped from her wand a moment later, she broke out in a wide grin.

The Slytherins seemed to have a particularly difficult time with this lesson. Professor Merrythougt sighed. "Ah, yes, it's always the same. I don't know why producing a patronus is so difficult for our Slytherin students. Just try your best, my dears."

Harry rather enjoyed listening to Abraxas Malfoy cursing under his breath. Only two of the Slytherin students managed to produce anything at all. One was little Alphard Black, who looked enormously pleased with himself. It was impossible to tell what his hazy patronus was, but it was something. Alphard spent the rest of the afternoon polling the other students about whether they thought his patronus looked more like a platypus or a starfish. The other Slytherin who produced a patronus was Tom. Harry stared in wonder as a silvery animal leaped from Tom' yew wand towards the end of the lesson. What was it? It was not quite distinct enough to tell, but it was not a serpent. It was a rather large animal with four legs; that was all Harry was able to make out.

None of the death eaters are able to produce a patronus, so how can you, Tom?

Harry felt uneasy. Why was Professor Merrythought insisting that they all learn about patronuses so suddenly? What would they need to defend themselves against?

He kept walking into small groups of students huddled around the most recent issues of The Daily Prophet. Harry was able to read a few headlines over Algie's shoulder: "Grindelwald's Troops Slay Thousands", "More Muggles Tortured", "Death Tolls Rise in Europe"…

"Oh, God," Algie whispered, white-faced. "All those innocent people… Why can't someone stop him? Why can't anyone do anything?"

Grindelwald… Harry recalled his name from a future chocolate frog card. Of course someone will stop him. Dumbledore will defeat Grindelwald.

But, wait a minute – Harry reached for the paper. Algie handed it to him silently and put his arms around his friend Enid's shoulder; she had relatives in Europe, and there was no news about their whereabouts yet.

No. No, this can't be right. Dumbledore defeats Grindelwald in 1945. But this is still 1942.

How could this be possible? He had to be wrong about the date. Dumbledore would not let Grindelwald continue his reign of terror for three years before defeating him in a duel, would he? But I'm not wrong about the date. It was the first chocolate card I ever got, and I spent weeks just staring at it. Dumbledore defeated the dark wizard Grindelwald in 1945. Three more years of terror?

Abruptly, Harry handed the paper back to Algie.

"What's the matter, Harry? Do you have missing relatives in Europe as well?" Harry was touched by the look of sympathy on Algie's pleasant round face.

"No, I just… I need to see Dumbledore."

He found Dumbledore in his office, a much smaller office than the one he was to have as headmaster, but oddly familiar nevertheless, a cramped little room filled with spinning silver instruments, old books and stacks of parchment. Fawkes the phoenix was in his cage as always, a magnificent burst of gold and scarlet plumes. He gave Harry a funny look, as if to say: "You again, my friend?"

"Ah, Harry!" Dumbledore greeted him warmly. "How are you doing, my dear boy? Would you care for a cockroach cluster?"

"Er… no, thanks."

"I can't say I blame you, Harry. They are disgusting, albeit in a curiously satisfying way. Sort of like – "

"Bertie Botts Every Flavored Beans?"

"What?" Dumbledore sounded genuinely puzzled. "What are they?"

Something that hasn't been invented yet, apparently.

"Oh," Harry smiled. "Just a sort of candy. Comes in absolutely every flavor."

There was a twinkle in Dumbledore's eye. "Every flavor? Merlin's beard, I hope not… But tell me how you are settling in, Harry."

"Oh, fine. But – but I need to ask you something, professor."

"Yes, of course, Harry. Have a seat, but make sure you don't sit on anything sticky."

Harry found a suitably unsticky chair and sat down. "Professor Dumbledore," he began, "there are all these things in the news about Grindelwald. About him killing people."

In spite of his still auburn hair and beard, Dumbledore suddenly looked old, as old as Harry had ever seen him.

"Yes." He sighed. "Yes, Harry, terrible things are happening. It's profoundly upsetting to all of us."

"So why don't you do something?" Harry jumped out of his chair and faced Dumbledore angrily. "Why don't you kill him? You are the one who is supposed to do it, so why don't you do it right now? Why don't you stop him from killing more innocent people?"

"I am the one - the one who is supposed to do it?" Dumbledore's voice was trembling, and Harry looked at him wonderingly.

"Yes, Professor. Don't you remember?"

Can Dumbledore remember the future? He did remember me – what about Grindelwald?

"I – no, I'm not sure, Harry. It is true that I am an occasional traveler, much like yourself, and that I have been known to roam here and there, but this… There are things about the future that are hard to recall."

Were those tears in his eyes?

"You had better remind me, Harry," he said softly.

Harry took a deep breath. "Professor, you are supposed to kill Grindelwald. There will be a great duel, between the two of you, and you will win. He will die by your hand. And that will put an end to all this terror, to all the innocent people dying."

"I… I see, Harry. Thank you for telling me this."

"But Professor Dumbledore," Harry burst out, "I don't understand. You – you will defeat Grindelwald in 1945! I read it on a chocolate frog card. But that's three years from now. Thousands… tens of thousands of innocent people will die before then. You can't wait! You have to do it now, you must kill him now!"

Dumbledore's head was bent as he whispered. "Yes, I suppose you are right, Harry. I suppose I must."

"Then what are you waiting for?" Harry looked at Dumbledore in exasperation.

"Oh, Harry," Dumbledore's voice was trembling. "I know what I have to do. But it is - extraordinarily difficult for me to do what I must."

"Why? He's killing people! He's a monster."

"A monster, yes." Dumbledore voice was very quiet. "But you see, Harry, he is my friend as well."

"Your friend? Grindelwald is your friend?"

Dumbledore nodded. A tear rolled slowly down his cheek. "Before he became a monster, he was my friend. My friend, and more than a friend…"

"Like…" How difficult it was to get the words out! "Like Gryffindor and Slytherin?"

A brief smile crossed Dumbledore's face. "Yes, Harry," he said softly. "Like Gryffindor and Slytherin. He was very different then, you see, when we were young. He was my companion, my equal, someone with a heart and mind very much like my own."

"A second self. A stormy heart for my stormy heart." The words sprang unbidden to Harry's lips.

"The story of Gilgamesh?" Dumbledore smiled a little. "Yes, I suppose it was like that. Except that Gilgamesh' cruel heart was changed by his friendship with the innocent Enkidu, and Grindelwald's heart could never lose its cruelty. There was a darkness in him that could not be redeemed. I loved him. I still do. Yes, I am ashamed to admit it: I love him even after reading about the atrocities in the news. I wish I did not. An odd thing, the human heart, isn't it? I love him. And now, I have to become his murderer."

His murderer. How can he kill the person he loves? And yet, how can he not?

I know how he feels-

Harry leaned against the wall. He felt sick at heart.

"It's not easy, is it, Harry?" came Dumbledore's voice softly.

"No – "

"And yet, we must do what we must do."

"Yes," Harry whispered. "I suppose we must."

The next day, he learned that Dumbledore had left the school for an important mission abroad and would not return for some time. History will change. The chocolate frog cards will proclaim 1942 to be the date of Dumbledore's greatest victory. This thought should have made Harry feel better, but somehow, it did not.

Dumbledore is a courageous man indeed. No one will ever know how much this victory will cost him.

Harry walked slowly through the Hogwarts grounds at twilight, trying to come to terms with the impossible task that lay ahead. I must do what I must do. Or else a second Grindelwald will arise, more terrifying than the first. Voldemort's reign will be worse than any the world has known. I must become a murderer so Tom will not.

"There you are, Harry!" Tom's familiar voice called out to him from somewhere nearby. "Watch this!"

The shimmering silver form of a patronus, haunting in its loveliness in that twilight hour, came towards him. It was a stag.