“Snape,” repeated McGonagall faintly,

“Snape,” repeated McGonagall faintly, falling into the chair. “We all wondered... but he trusted... always... Snape... I can't believe it...”

“Snape was a highly accomplished Occlumens,” said Lupin, his voice uncharacteristically harsh. “We always knew that.”

“But Dumbledore swore he was on our side!” whispered Tonks. “I always thought Dumbledore must know something about Snape that we didn't...” .

“He always hinted that he had an ironclad reason for trusting Snape,” muttered Professor McGonagall, now dabbing at the corners of her leaking eyes with a tartan-

edged handkerchief. “I mean... with Snape's history ... of course people were bound to wonder... but Dumbledore told me explicitly that Snape's repentance was

absolutely genuine... wouldn't hear a word against him!”

“I'd love to know what Snape told him to convince him,” said Tonks.

“I know,” said Harry, and they all turned to look at him. “Snape passed Voldemort the information that made Voldemort hunt down my mum and dad. Then Snape told

Dumbledore he hadn't realized what he was doing, he was really sorry he'd done it, sorry that they were dead.”

They all stared at him.

“And Dumbledore believed that?” said Lupin incredulously. “Dumbledore believed Snape was sorry James was dead? Snape hated James...”

“And he didn't think my mother was worth a damn either,” said Harry, “because she was Muggle-born... ‘Mudblood,’ he called her...”

Nobody asked how Harry knew this. All of them seemed to be lost in horrified shock, trying to digest the monstrous truth of what had happened.

“This is all my fault,” said Professor McGonagall suddenly. She looked disoriented, twisting her wet handkerchief in her hands. “My fault. I sent Filius to fetch

Snape tonight, I actually sent for him to come and help us! If I hadn't alerted Snape to what was going on, he might never have joined forces with the Death Eaters. I

don't think he knew they were there before Filius told him, I don't think he knew they were coming.”

“It isn't your fault, Minerva,” said Lupin firmly. “We all wanted more help, we were glad to think Snape was on his way....”

“So when he arrived at the fight, he joined in on the Death Eaters’ side?” asked Harry, who wanted every detail of Snape's duplicity and infamy, feverishly

collecting more reasons to hate him, to swear vengeance.

“I don't know exactly how it happened,” said Professor McGonagall distractedly. “It's all so confusing... Dumbledore had told us that he would be leaving the school

for a few hours and that we were to patrol the corridors just in case... Remus, Bill, and Nymphadora were to join us ... and so we patrolled. All seemed quiet. Every

secret passageway out of the school was covered. We knew nobody could fly in. There were powerful enchantments on every entrance into the castle. I still don't know how

the Death Eaters can possibly have entered...”

“I do,” said Harry, and he explained, briefly, about the pair of Vanishing Cabinets and the magical pathway they formed. “So they got in through the Room of

Requirement.”