A few sparks shot out of the end of his wand, which was still pointed at Black’s face. Hermione fell silent.
“Vengeance is very sweet,” Snape breathed at Black. “How I hoped I would be the one to catch you…”
“The joke’s on you again, Severus,” Black snarled. “As long as this boy brings his rat up to the castle”—he jerked his head at Ron—“I’ll come quietly…”
“Up to the castle?” said Snape silkily. “I don’t think we need to go that far. All I have to do is call the Dementors once we get out of the Willow. They’ll be very pleased to see you, Black… pleased enough to give you a little kiss, I daresay… I—”
What little color there was in Black’s face left it.
“You—you’ve got to hear me out,” he croaked. “The rat—look at the rat—”
But there was a mad glint in Snape’s eyes that Harry had never seen before. He seemed beyond reason.
“Come on, all of you,” he said. He clicked his fingers, and the ends of the cords that bound Lupin flew to his hands. “I’ll drag the werewolf. Perhaps the Dementors will have a kiss for him too—”
Before he knew what he was doing, Harry had crossed the room in three strides and blocked the door.
“Get out of the way, Potter, you’re in enough trouble already,” snarled Snape. “If I hadn’t been here to save your skin—”
“Professor Lupin could have killed me about a hundred times this year,” Harry said. “I’ve been alone with him loads of times, having defense lessons against the Dementors. If he was helping Black, why didn’t he just finish me off then?”
“Don’t ask me to fathom the way a werewolf’s mind works,” hissed Snape. “Get out of the way, Potter.”
“YOU’RE PATHETIC!” Harry yelled. “JUST BECAUSE THEY MADE A FOOL OF YOU AT SCHOOL YOU WON’T EVEN LISTEN—”
“SILENCE! I WILL NOT BE SPOKEN TO LIKE THAT!” Snape shrieked, looking madder than ever. “Like father, like son, Potter! I have just saved your neck; you should be thanking me on bended knee! You would have been well served if he’d killed you! You’d have died like your father, too arrogant to believe you might be mistaken in Black—now get out of the way, or I will make you. GET OUT OF THE WAY, POTTER!”
Harry made up his mind in a split second. Before Snape could take even one step toward him, he had raised his wand.
“Expelliarmus!” he yelled—except that his wasn’t the only voice that shouted. There was a blast that made the door rattle on its hinges; Snape was lifted off his feet and slammed into the wall, then slid down it to the floor, a trickle of blood oozing from under his hair. He had been knocked out.
Harry looked around. Both Ron and Hermione had tried to disarm Snape at exactly the same moment. Snape’s wand soared in a high arc and landed on the bed next to Crookshanks.
“You shouldn’t have done that,” said Black, looking at Harry. “You should have left him to me…”