But Harry couldn’t run. Ron was chained to Pettigrew and Lupin. He leapt forward but Black caught him around the chest and threw him back.
“Leave it to me—RUN!”
There was a terrible snarling noise. Lupin’s head was lengthening. So was his body. His shoulders were hunching. Hair was sprouting visibly on his face and hands, which were curling into clawed paws. Crookshanks’s hair was on end again; he was backing away—
As the werewolf reared, snapping its long jaws, Sirius disappeared from Harry’s side. He had transformed. The enormous, bearlike dog bounded forward. As the werewolf wrenched itself free of the manacle binding it, the dog seized it about the neck and pulled it backward, away from Ron and Pettigrew. They were locked, jaw to jaw, claws ripping at each other.
Harry stood, transfixed by the sight, too intent upon the battle to notice anything else. It was Hermione’s scream that alerted him—
Pettigrew had dived for Lupin’s dropped wand. Ron, unsteady on his bandaged leg, fell. There was a bang, a burst of light—and Ron lay motionless on the ground. Another bang—Crookshanks flew into the air and back to the earth in a heap.
“Expelliarmus!” Harry yelled, pointing his own wand at Pettigrew; Lupin’s wand flew high into the air and out of sight. “Stay where you are!” Harry shouted, running forward.
Too late. Pettigrew had transformed. Harry saw his bald tail whip through the manacle on Ron’s outstretched arm and heard a scurrying through the grass.
There was a howl and a rumbling growl; Harry turned to see the werewolf taking flight; it was galloping into the forest—
“Sirius, he’s gone, Pettigrew transformed!” Harry yelled.
Black was bleeding; there were gashes across his muzzle and back, but at Harry’s words he scrambled up again, and in an instant, the sound of his paws faded to silence as he pounded away across the grounds.
Harry and Hermione dashed over to Ron.
“What did he do to him?” Hermione whispered. Ron’s eyes were only half closed, his mouth hung open; he was definitely alive, they could hear him breathing, but he didn’t seem to recognize them.
“I don’t know…”
Harry looked desperately around. Black and Lupin both gone… they had no one but Snape for company, still hanging, unconscious, in midair.
“We’d better get them up to the castle and tell someone,” said Harry, pushing his hair out of his eyes, trying to think straight. “Come—”
But then, from beyond the range of their vision, they heard a yelping, a whining: a dog in pain…
“Sirius,” Harry muttered, staring into the darkness.
He had a moment’s indecision, but there was nothing they could do for Ron at the moment, and by the sound of it, Black was in trouble—
Harry set off at a run, Hermione right behind him. The yelping seemed to be coming from the ground near the edge of the lake. They pelted toward it, and Harry, running flat out, felt the cold without realizing what it must mean—