McGonnagal looked around the hall at the defenders waiting for instructions, finally spotting Hagrid standing in the shadow of the massive door. A nearby torch seemed to lend his eyes an unnerving gleam.

"Hagrid!" she called, causing many to turn around and stare at him. "Professor?" he asked in his gruff voice, though they both knew what she was going to say.

Adopting a sombre tone, she began reciting the words Dumbledore taught her so long ago.

"Night falls. Until the sun rises, you will go out and kill all those who would harm Hogwarts or her children," she said, dreading what was to come.

The hall grew dead silent, no one believing what they had just heard or to whom it had been said. Steeling her nerves, McGonnagal continued,

" From blameless bodies blood is shed;
Now the ghouls become undead;
The bird of Hermes rises soon;
Not morning, night, or afternoon;
The Bird of Hermes is my name;
Eating my wings, to keep you tame."

Hagrid grew absolutely still as she spoke, not even breathing, before responding in a voice no one now living had ever heard.

"The bird of Hermes fees on fright;
Soon sinful blood shall stain the night;
The bird of Hermes will devour;
His master's foes at the final hour;
The bird of Hermes is my name;
Eating my wings to keep me tame.
Releasing restraint level zero."

As he spoke, his voice deep and resounding as though coming from a great depth, his beard and most of his clothes seemed to melt away. His hair, previously thick and tangled, straightened and gained a black lustre. As though soot-stained wire. His already large frame bulged as massive muscles now corded his arms, torso, and what could be seen of his legs underneath his trousers. As he spoke the final line of the old invocation, two thick, black horns sprouted from his forehead, curving around his ears and back along his jaw as though those of some infernal ram. His feet shrunk and hardened into an almost oversized pair of hooves.

"Headmistress," the newly-revealed demon rumbled, "I believe I would like to go for a walk." Turning to the children and adults, now clustered around the professor in fear and horror, he continued. "I suggest you not go outside. This is not for your eyes…