Bellatrix’s mouth twisted as though she had taken an unpleasant dose of medicine.
“But you didn’t return when he came back, you didn’t fly back to him at once when you felt the Dark Mark burn—”
“Correct. I returned two hours later. I returned on Dumbledore’s orders.”
“On Dumbledore’s—?” she began, in tones of outrage.
“Think!” said Snape, impatient again. “Think! By waiting two hours, just two hours, I ensured that I could remain at Hogwarts as a spy! By allowing Dumbledore to think that I was only returning to the Dark Lord’s side because I was ordered to, I have been able to pass information on Dumbledore and the Order of the Phoenix ever since! Consider, Bellatrix: The Dark Mark had been growing stronger for months. I knew he must be about to return, all the Death Eaters knew! I had plenty of time to think about what I wanted to do, to plan my next move, to escape like Karkaroff, didn’t I?
“The Dark Lord’s initial displeasure at my lateness vanished entirely, I assure you, when I explained that I remained faithful, although Dumbledore thought I was his man. Yes, the Dark Lord thought that I had left him forever, but he was wrong.”
“But what use have you been?” sneered Bellatrix. “What useful information have we had from you?”
“My information has been conveyed directly to the Dark Lord,” said Snape. “If he chooses not to share it with you—”
“He shares everything with me!” said Bellatrix, firing up at once. “He calls me his most loyal, his most faithful—”
“Does he?” said Snape, his voice delicately inflected to suggest his disbelief. “Does he still, after the fiasco at the Ministry?”
“That was not my fault!” said Bellatrix, flushing. “The Dark Lord has, in the past, entrusted me with his most precious—if Lucius hadn’t—”
“Don’t you dare—don’t you dare blame my husband!” said Narcissa, in a low and deadly voice, looking up at her sister.
“There is no point apportioning blame,” said Snape smoothly. “What is done, is done.”
“But not by you!” said Bellatrix furiously. “No, you were once again absent while the rest of us ran dangers, were you not, Snape?”
“My orders were to remain behind,” said Snape. “Perhaps you disagree with the Dark Lord, perhaps you think that Dumbledore would not have noticed if I had joined forces with the Death Eaters to fight the Order of the Phoenix? And—forgive me—you speak of dangers… you were facing six teenagers, were you not?”
“They were joined, as you very well know, by half of the Order before long!” snarled Bellatrix. “And, while we are on the subject of the Order, you still claim you cannot reveal the whereabouts of their headquarters, don’t you?”
“I am not the Secret-Keeper; I cannot speak the name of the place. You understand how the enchantment works, I think? The Dark Lord is satisfied with the information I have passed him on the Order. It led, as perhaps you have guessed, to the recent capture and murder of Emmeline Vance, and it certainly helped dispose of Sirius Black, though I give you full credit for finishing him off.”