“Harry, you were never a good Occlumens —”
The word was the spark that ignited Harry’s fury.
“Snape!” he said, very loudly, and Fawkes gave a soft squawk behind them. “Snape’s what’s happened! He told Voldemort about the prophecy, it was him, he listened outside the door, Trelawney told me!”
Dumbledore’s expression did not change, but Harry thought his face whitened under the bloody tinge cast by the setting sun. For a long moment, Dumbledore said nothing. “When did you find out about this?” he asked at last.
“Just now!” said Harry, who was refraining from yelling with enormous difficulty. And then, suddenly, he could not stop himself. “AND YOU LET HIM TEACH HERE AND HE TOLD VOLDEMORT TO GO AFTER MY MUM AND DAD!”
Breathing hard as though he was fighting, Harry turned away from Dumbledore, who still had not moved a muscle, and paced up and down the study, rubbing his knuckles in his hand and exercising every last bit of restraint to prevent himself knocking things over. He wanted to rage and storm at Dumbledore, but he also wanted to go with him to try and destroy the Horcrux; he wanted to tell him that he was a foolish old man for trusting Snape, but he was terrified that Dumbledore would not take him along unless he mastered his anger. . . .
“Harry,” said Dumbledore quietly. “Please listen to me.”
It was as difficult to stop his relentless pacing as to refrain from shouting. Harry paused, biting his lip, and looked into Dumbledore’s lined face.
“Professor Snape made a terrible —”
“Don’t tell me it was a mistake, sir, he was listening at the door!”
“Please let me finish.” Dumbledore waited until Harry had nodded curtly, then went on. “Professor Snape made a terrible mistake. He was still in Lord Voldemort’s employ on the night he heard the first half of Professor Trelawney’s prophecy. Naturally, he hastened to tell his master what he had heard, for it concerned his master most deeply. But he did not know — he had no possible way of knowing — which boy Voldemort would hunt from then onward, or that the parents he would destroy in his murderous quest were people that Professor Snape knew, that they were your mother and father —”
Harry let out a yell of mirthless laughter.
“He hated my dad like he hated Sirius! Haven’t you noticed, Professor, how the people Snape hates tend to end up dead?”
“You have no idea of the remorse Professor Snape felt when he realized how Lord Voldemort had interpreted the prophecy, Harry. I believe it to be the greatest regret of his life and the reason that he returned —”
“But he’s a very good Occlumens, isn’t he, sir?” said Harry, whose voice was shaking with the effort of keeping it steady. “And isn’t Voldemort convinced that Snape’s on his side, even now? Professor . . . how can you be sure Snape’s on our side?”
Dumbledore did not speak for a moment; he looked as though he was trying to make up his mind about something. At last he said, “I am sure. I trust Severus Snape completely.”
Harry breathed deeply for a few moments in an effort to steady himself. It did not work.
“Well, I don’t!” he said, as loudly as before. “He’s up to something with Draco Malfoy right now, right under your nose, and you still —”
“We have discussed this, Harry,” said Dumbledore, and now he sounded stern again. “I have told you my views.”
“You’re leaving the school tonight, and I’ll bet you haven’t even considered that Snape and Malfoy might decide to —”
“To what?” asked Dumbledore, his eyebrows raised. “What is it that you suspect them of doing, precisely?”
“I . . . they’re up to something!” said Harry, and his hands curled into fists as he said it. “Professor Trelawney was just in the Room of Requirement, trying to hide her sherry bottles, and she heard Malfoy whooping, celebrating! He’s trying to mend something dangerous in there and if you ask me, he’s fixed it at last and you’re about to just walk out of school without —”
“Enough,” said Dumbledore. He said it quite calmly, and yet Harry fell silent at once; he knew that he had finally crossed some invisible line. “Do you think that I have once left the school unprotected during my absences this year? I have not. Tonight, when I leave, there will again be additional protection in place. Please do not suggest that I do not take the safety of my students seriously, Harry.”
“I didn’t —” mumbled Harry, a little abashed, but Dumbledore cut across him.
“I do not wish to discuss the matter any further.”
Harry bit back his retort, scared that he had gone too far, that he had ruined his chance of accompanying Dumbledore, but Dumbledore went on, “Do you wish to come with me tonight?”
“Yes,” said Harry at once.
“Very well, then: Listen.” Dumbledore drew himself up to his full height. “I take you with me on one condition: that you obey any command I might give you at once, and without question.”
“Of course.”
“Be sure to understand me, Harry. I mean that you must follow even such orders as ‘run,’ ‘hide,’ or ‘go back.’ Do I have your word?”
“I — yes, of course.”
“If I tell you to hide, you will do so?”
“Yes.”
“If I tell you to flee, you will obey?”
“Yes.”
“If I tell you to leave me and save yourself, you will do as I tell you?”
“I —”
“Harry?”
They looked at each other for a moment.
“Yes, sir.”
“Very good. Then I wish you to go and fetch your Invisibility Cloak and meet me in the entrance hall in five minutes’ time.”
Dumbledore turned back to look out of the fiery window; the sun was now a ruby red glare along the horizon. Harry walked quickly from the office and down the spiral staircase. His mind was oddly clear all of a sudden. He knew what to do.