The stone floor shook as a loud crash from the room below reverberated throughout the school, followed by a shout of either pain or rage. The Doctor couldn't tell which as he rushed down the hallway and desperately tried to remember how to reach the main stairway from the hospital wing. He almost flew right by the correct hallway in his mad dash towards the battle, and he nearly plowed directly into the wall in his effort to skid around the corner. The Doctor shook his head and ran to the rotating staircases, which had stopped moving mid-transition, leaving large gaps of space between the different levels. A cluster of frightened first year students were huddled together on the landing. One small girl shrieked as a bolt of green light flew past them and she buried her head into another boy's shoulder.

"Professor!" one of the students cried, her brown eyes filled with tears. "Professor, what's happening? Who's down there?"

The Doctor crouched down and rubbed her back. "Hey, hey, it's all right. I'm going down there to make sure it's all okay. I need you to do something for me, though." The girl nodded at him, making her black curly hair bounce up and down. "I need you all to get out of here and head towards the hospital wing. Can you do that? Okay, good, allons-y!" The children scrambled to their feet and back down the hallway the Doctor had come from.

Once he was sure the children were far away from the commotion below, the Doctor judged the distance between the staircases. He frowned as his estimation amounted to a distance a bit too long for him to jump. Maybe since gravity is on my side, I could make it, he thought, but he still hesitated at the ledge.

Another shout from below, followed by several cries of dismay. Before he could fully process what he was doing, he backed up a few steps and launched himself into the air.

For a millisecond, it looked as though he might clear the distance, but he fell just a few centimeters short. The Doctor instinctively threw his hands up to try and grab on to the railing as he plummeted past the staircase. His hand slipped off the handrail, but he managed to grip onto the base of the stone steps before he fell the rest of the distance to the hard ground far below. Panting heavily as he dangled in the air, just a few seconds away from free-falling his way to either death or many, many broken bones, the Doctor tried to get a good look at the next staircase that seemed to be almost directly beneath him. It looked about six meters away. He didn't want to think too much about what he was doing, so he let go and braced himself for the crash.

The air whistled past him before he crashed onto the unforgiving stone below, and instead of sticking the landing as he'd planned, his momentum made him topple down the stairs. He crashed into the wall and lay in a stunned heap for a moment. When the ceiling stopped swirling in front of him, he rolled over and used the rail to pull himself up. A grateful glance at the path ahead of him showed that these stairs were much closer together and well within anyone's jumping capability. After giving himself one more second to clear his head, he hurried down the stairs and made his way to the commotion.

"Duck!" shouted a hoarse voice to his left. Instinctively, the Doctor dropped. A stream of green light passed over his head and hit the wall behind him. There was a brief echo of cracking rock.

The Doctor looked towards where the curse had come from. A tall blond man was running away from the scene and firing more green curses into a mass of dueling wizards made up of adults and children alike. Flashes and bangs erupted periodically as the black-robed intruders pressed ever closer towards the staircase leading up to the Astronomy tower, while students and some adults the Doctor had never seen before countered the attacks and tried to force them back.

A hand appeared at the Doctor's elbow. He looked up into the scarred face of a man wearing shabby robes. "Are you hurt?" the man asked quickly.

"Oh, nah, I'm fine, what's happening here?" the Doctor asked.

"There's no time to explain - we have to defend the school from the Death Eaters." The man helped the Doctor to his feet then ran after the blond attacker with his wand brandished in front of him.

"Oh, is that it?" the Doctor muttered as he dashed into the fray. There were lots of shouts, though he couldn't make out specific sentences. He thought he heard the names "Dumbledore" and "Draco" as two curses whizzed past him.

"Somebody help! Over here!" shouted a voice. The Doctor saw a young woman trying to pull an enormous man away from a fallen body. "Stop it - get off him…!" she yelled. The man snarled and grabbed her arms. His eyes had a feral gleam to them and his mouth and hands were smeared with deep red blood.

The Doctor was there in an instant. He whipped out his sonic screwdriver and jabbed it into the man's spine. The man howled as volts of electricity assaulted his body. After a few seconds, he released the woman's arms and scampered away. The Doctor was tempted to follow him, but his more immediate concern was the still body on the floor. The wounded young man was bleeding in multiple places and his face was covered in what looked like bite marks, but the Doctor could feel a hammering pulse in his throat.

"His name is Bill - is he…?"

The Doctor looked up, and was surprised to see that the woman's eyes had actually changed from brown to blue as she looked at him fearfully. "He's still alive, but he needs a doctor. A proper doctor, mind you, not me."

The woman's eyes switched back to brown as she visibly relaxed. "Get him out of here while we take care of the Death Eaters," she said forcefully. She turned to counter an attack from another dark figure and led him away from the Doctor and Bill.

"I just said not me, a real doctor!" the Doctor shouted after her, but she was already gone. "Why does no one ever listen to me?" he asked Bill, who predictably did not answer.

A stray spell sent a spray of dust and rocks over them, and the Doctor threw himself over Bill to protect him from further injury. A sharp shard caught him over the eye and opened up a cut on his forehead. He swiped the blood out of his vision as he twisted the settings on the screwdriver.

"33D, we go, 33F," he said, and passed the blue light over the deep gouges on Bill's face. Bill grunted as the wounds were sanitized, but otherwise didn't respond. The Doctor tucked his hands underneath Bill's armpits and started to drag him away from the main conflict.

"They're breaking away!" yelled a desperate voice. Ron, the Doctor thought.

"Don't let them up the stairs - "

"Those four are - "

"Watch it!"

The Doctor lost his grip on Bill as someone boomed an incantation that sent out a pressure wave across the hallway. In the instant that he was distracted, one of the attacking Death Eaters appeared at his side.

"Going somewhere?" he sneered. He raised his wand and brought it down in a violent slashing motion. The Doctor dove out of the way as a column of fire blazed past where he had been standing. Before the Death Eater had time to attack again, he bounded up and caught the man's wrist.

"Oi! Careful! You'll put someone's eye out, flapping around like that!" the Doctor warned as he squeezed his hand and forced the man to drop his wand. He then quickly pressed his fingertips against the man's temples and sent him to sleep. The Death Eater's eyes rolled up in their sockets. He slumped forward and would have crashed to the ground if the Doctor hadn't caught him and gently lowered him down.

A sharp crack sounded from the main stairs the Death Eaters had been trying to surmount. Neville, it seemed, had tried to pursue them and had been thrown back. "There's some sort of invisible barrier they've put up. We can't get through it!" Neville said as the woman with the changing eyes helped him to his feet.

"There must be some way to get past it…" said the scarred man as he aimed a bolt of blue light at the blond Death Eater that had descended on Neville.

The Doctor shoved his hands underneath Bill's arms and dragged him to the wall, where he hopefully would be at least a little safer. Then he hurried to the stairs where the invisible barrier was. In the few free seconds he had while the Death Eaters were engaged with the wizards, he scanned the barrier for any anomalies.

"It looks like they've constructed some sort of electromagnetic repulsion field, though I don't know where they could possibly be getting the energy from, given its size…" the Doctor said, mainly to himself.

"Incoming!" a voice shouted. The Doctor jumped aside as another green curse rocketed past him and disintegrated against the barrier. Ginny Weasley appeared next to him, breathless from the fight. "Can you get rid of it?" she asked.

"Give me some time and I'll think of something," the Doctor assured her.

Ginny nodded. "I'll cover you," she said. She held her wand protectively against her chest as she scanned the fight for any oncoming attackers.

The Doctor knelt down and began twirling the settings of the sonic screwdriver. "The electromagnetic field is rotating in one specific direction, which is keeping us from breaching it," he babbled. "If I was to reverse the direction of the electron flow, I think it would give us a split second to destroy it before the electrons get going in the opposite direction…"

Ginny lashed out her wand against a curse coming their way. "What do you need, professor?"

The Doctor stood and pulled her closer to whisper into her ear. "I'm going to cause a distraction. I need you to be ready to send any sort of destructive spell through the barrier when I say so. Oh, and I'll need your wand."

Ginny's eyes widened, but she nodded and held out her wand. The Doctor took it and turned it over in his hands. "Well, it's not exactly sonic per say, but this should work," he said. He touched the tips of his sonic screwdriver and the wand together, and then pressed down on the screwdriver's activation button.

Instantly, the two devices produced a shrill keening that seemed to pierce straight through everyone's ear drums. Around the room, the duelists dropped their wands in favor of covering their ears in a frantic attempt to block out the sound. When he was sure everyone was thoroughly incapacitated, he let go of the button and the ringing stopped. Before anyone could get their bearings, he aimed the screwdriver at the barrier and reversed the direction of the electrons. "Now, Ginny!" he said urgently, pressing the wand into her hands.

Her face still screwed in pain against the Doctor's 'distraction', Ginny flung her wand blindly behind her and shot at the barrier. While she managed to hit it with her eyes closed, the hex was aimed high and it collided with the ceiling as well. As the barrier collapsed, the ceiling collapsed with it. When the resulting outburst of energy was released, large chunks of stone were hurled across the room at the barely-recovered wizards.

"Everyone drop!" the Doctor called out in the instant while the rocks sailed through the air. Almost everyone managed to avoid the onslaught, except Neville who took a forceful blow to the head and fell to the ground.

McGonagall was the first on her feet. "Quickly, up the stairs," she started, but the moment she said this, Snape and Malfoy emerged from the other side of the obliterated barrier. It appeared they were being pursued by the group of Death Eaters that had bypassed their defenses earlier. "Let them through! Focus on the Death Eaters!" she commanded.

"It's Harry!" Ginny suddenly said, even as she and the Doctor dodged around a giggling woman firing hexes in their direction. "Look, there he goes - "

The Doctor held her back from chasing after him. "Don't worry about Harry, he'll be all right, focus on keeping yourself safe."

"He'll need help…" Ginny protested.

"I'll go after him since I can't do much else here," the Doctor said. He pushed her back towards the resumed battle. "Go help your friends."

Ginny looked torn as she stared down the hallway Harry had disappeared down, but with a groan she turned away and dashed back into the thick of the fight. The Doctor felt a twinge of guilt that he had really just sent a teenager into probable harm, but he didn't have time to agonize over it. He quickly slipped away to follow Harry and hopefully keep him out of harm's way.

Harry had a large head start on him, but the Doctor had a feeling that he had run outside. His sprint to the front grounds seemed interminable as he didn't know the castle's hallways as well as Harry did. When he finally reached the front doors and saw the burn marks that scored the oak paneling, he feared for the worst. His anxiety mounted as he saw Harry's distant figure dashing after Snape and Malfoy, illuminated by the burning building behind them.

The Doctor couldn't make out exactly what Harry was doing, but he doubled his speed when he saw Snape turn with his wand outstretched. Harry flew backwards and hit the grass hard. Another Death Eater turned his wand on Harry as well, and for a moment Harry doubled over and screamed in pain before Snape pushed the Death Eater away and cut off the spell.

"Snape!" the Doctor shouted, trying to distract him from Harry as he ran across the grass. However Snape's attention was focused solely on Harry, and the Doctor could do nothing as Snape yelled something about being a prince and attacked Harry once again. He closed the last stretch of distance and hurriedly knelt down at Harry's head. Harry seemed to be having trouble focusing on him, and he didn't respond when the Doctor tapped his face gently.

"Doctor," Snape said, his normally cool tone harsh with anger. "If I wasn't in a hurry, I would not hesitate to cut you down where you stand."

"Lucky for me you're in such a hurry, then," the Doctor snarled. Snape's lip twisted into a grotesque sneer. He turned and ran with a dramatic flourish of his robes. The Doctor would have chased him if Harry hadn't needed immediate attention.

In the grass next to him, Harry shook his head as if to clear it, and when he spoke for the first time, his words came out too slurred for the Doctor to understand. He leaned in closer to try and make out what he was saying.

What he heard shocked him more than anything else had that entire night.

"Dead," Harry croaked out. "Dumbled… Dumbledore's dead."

A/N this chapter wins the most-frustrating-chapter-ever award. what an accomplishment. sorry about the super long wait for this mess ha ha ha