It had been evening when the four returned to Grimmauld Place, and the revelations of that day had left the golden trio exhausted. Karn suggested that they rest and restore themselves before going into what would certainly be a battle at Hogwarts.

Before going to bed, Harry asked Karn about his scar - the scar he now knew held a piece of the Dark Lord.

"There is magic there, as you suspected," Karn said. His hand glowed with a soft yellow light as his magic scanned the area. "You said something about being linked to the Dark Lord?"

Harry nodded. "I can see what he sees, sometimes. Usually when he is emotional or angry."

"Interesting," replied Karn, lowering his hand. "That may be a powerful weapon against him, if the need arises." Karn saw the uncertainty on Harry's face at that thought.

"I don't want him to know what I'm thinking," Harry said. "If he knows we are after a horcrux, he will order an attack on the school."

"That is likely," Karn agreed. "Fortunately, you will know when the goblins inform him of your escape. We will have some warning."

"Why would the goblins do that?" asked Harry, with a frown. "They claim to be neutral."

"With that many of the creatures working for the bank," Karn said, "it would be trivial to subvert at least a few. Any force seeking to take over your world would need to know what the goblins were doing." Karn's yellow eyes focused on Harry's. "It only takes one spy to reveal the secret."

A sigh escaped Harry. "Then we're out of time."

"Yes."

Harry chose that moment to yawn, the fatigue rapidly catching up to him. "If he moves, I'll know it and wake everyone. Until then, I need to get some rest." He looked up at Karn, a sudden look of concern on his face. "Karn, do you need anything?" He left the question he wanted to ask - Do you sleep? - unspoken.

Karn\s voice sounded amused. "No, I do not need to sleep." The golem looked around the kitchen briefly, before returning his attention to his host. "If you happen to have a small supply of metal, I would be grateful."

"Metal?" Harry could not help but be confused by the request. Did Karn actually eat metal for food? Or was there some other purpose to the question? Another yawn interrupted his thoughts, and Harry decided that the reasons really didn't matter, not tonight. He gestured toward a door in the corner. "The basement is through that door. If no one has stolen it, there should be some old junk that may be useful to you."

Karn inclined his head in thanks. "It is appreciated, young mage."

Any reply harry might have offered was swallowed by another yawn. Taking that as his cue, Harry went to bed.

The silver golem watched Harry walk up the stairs, his yellow eyes glowing with unearthly light. His expression, as it had been for much of the night, was unreadable.

oOoOoOoOo

When Hermione Granger stepped out of her room the following morning, she was startled by the sound of a man's voice coming from the foyer. The voice was not one she recognized, though his tone was light and conversational. It certainly didn't sound like a death eater, of that she was sure.

It was the calm response from the portrait of Walburga Black that truly confused her, for she had never heard the portrait have a polite conversation. Drawing her wand, she stepped quietly toward the landing.

When she reached the top of the stairs, she saw a man standing in the foyer, leaning against the wall, having a nice little chat with the angriest painting in the wizarding world. The man was tall and well-built, and wore an outfit that made Hermione think of a pirate captain. His dark hair and beard framed a face that was at once both kind and determined. He had the look of someone who was used to command, but did not enjoy it.

His eyes were drawn to her when she came into view. "Name's Gerrard, at your service." he said, smiling.

Hermione's mind was racing. Clearly, the wards had allowed this man into the house, so he couldn't be a threat. But Harry owned the house, and would have to have known this person, right? She kept her eyes on Gerrard, who seemed amused at her confusion.

The man hooked a thumb toward the kitchen door. "I'm a friend of Big Shiny, in there."

"I have asked you repeatedly to stop using that name, Gerrard," came the reply from Karn. The voice remained even, with no hint of annoyance - which only made the odd man grin.

"Aye aye," he said.

Hermione couldn't help but chuckle. "So you are from Karn's world, then?" she asked.

Gerrard shrugged. "That, my dear, is a very long story." He nodded toward her, and she looked down to see her wand still in hand. "Perhaps we could sit down and talk about it? Without our weapons?"

Hermione hesitated just slightly, before putting her wand away. Karn trusts him, she thought, making her decision an easy one.

When she reached the bottom of the stairs, Gerrard held out a hand. Taking Hermione's, he placed a kiss on her knuckles.

"A pleasure, Miss Granger," he said. As he turned toward the kitchen, he did not notice her freeze in place. When he looked back, he saw that Hermione had her wand out once more.

"I don't remember telling you my name," she said. The ice in her tone told him how tightly she was controlling her anger.

"Ah, well," Gerrard began. "You didn't, actually."

"Then how do you know me?" She stepped forward, her wand aimed squarely at the man's forehead. "How are you here? Who are you?"

Gerrard smirked at her, and gave a jaunty little salute. Then, before her eyes, his form shimmered and vanished.

Hermione stood there, in the foyer, stunned by the disappearance. Again, the wards should have prevented it, but they failed. "How?" she said to herself.

"That would be my doing, Miss Granger," said Karn, apologetically. "Please, join us in the kitchen."

Not sure what she would find, Hermione walked to the kitchen door. Her eyes grew wide as they took in the sight before her.

Karn was sitting at the table, working on some sort of metal device. His hands were buried within the strange object, hidden from view. Above him, circling in a lazy arc, were three small dragonflies. Each was made of gleaming metal, and the quiet buzzing sound they made was a combination of wings and gears. Hermione found herself being reminded of clockwork, though the objects seemed far more complex.

A small creature, shorter than a house elf, stood on the table. As Hermione stepped forward, she saw that the creature was made of metal - two legs, four thin arms.

"Quite the sight, isn't it?"

Gasping, Hermione turned and saw Gerrard sitting against the far wall, the smirk still lighting his features. She did not even bother to raise her wand as she stared at the man, trying to puzzle out his secret. Gerrard noticed the expression, and nodded toward Karn.

The golem spoke without looking up from his work. "Gerrard was captain of skyship Weatherlight." Karn paused then, as if he didn't know how to continue.

"Was?" Hermione asked, unsure if she had heard him correctly.

"Aye," said Gerrard. "Karn here found me after my entire clan was murdered. When I grew up, we ended up saving each other's lives what, a dozen times each?"

"Considerably more, I believe," replied Karn, quietly.

"Something like that," Gerrard agreed. He leaned forward, tapping a finger on a small metal disc Hermione had ignored. Sitting on the table, the only indication of any sort of magic was a small blue light on its surface. The man smiled at her, before continuing. "When Karn decided to attempt to build something to cast an illusion, well… let's just say he picked someone he knew well."

"An illusion?" Hermione was shocked at the implication - Gerrard had held her hand. He had interacted with a portrait, and the portrait took him for human, or it would not have spoken, such was the magic of a wizarding painting. "How?"

Gerrard grinned again, before he shimmered and vanished.

"A combination of precisely formed energy shields and refracted light, Miss Granger," Karn said. Raising a hand, Karn summoned the metal disc, which obediently flew across the room. With a touch, the disc glowed once more, and Gerrard reappeared. "Magic would not be fooled, of course. But we're not attempting to fool magic."

"Nope. It's the men we need to fool, this time." The illusory captain leaned back in his chair, placing his boot-clad feet on the table and his hands behind his head. He was the very picture of relaxed as he spoke.

Hermione looked at the small disc in Karn's hand, and then back to Gerrard. "Amazing," was all she could say. She motioned to the dragonflies circling overhead. "And those?"

One of them broke formation and flew slowly across the room, stopping in a hover just in front of Hermione's face. The wings, she saw, were almost translucent, just like those of a real dragonfly. The body was multi-colored, as if more than one type of metal went into its construction. It even had small brass feet. Its head had one crystal eye, rather than the compound eyes of a real insect.

"Karn here is a master artificer, Miss Granger," answered Gerrard. The illusion smirked, as if remembering an old joke. "It always amused me that the most complicated artifact in the multiverse was the best at creating artifacts of his own."

Hermione looked back at Karn, who seemed to be focusing on the apparatus in front of him. Until that moment, she had not really contemplated the nature of their strange ally. "An artifact?" she said.

"Oh, aye." replied Gerrard. "On many worlds, you'll find devices capable of channeling magic. The vast majority are tools or weapons. Sometimes, there will be more unusual ones, like maybe a monument that shields a town, or a gate that can tell friend from foe."

"We can do some of that," Hermione said. "But we have to use runes and ward stones, and it's an incredibly complicated field of magic."

"That it is, Miss Granger, that it is," agreed Gerrard. He nodded toward Karn, and again Hermione looked over at the silver golem. "Many centuries ago, there was a man named Urza. He could blend magic and metal in ways no one had ever dreamed of before. One day, he decided to explore time itself, but the method he used would kill instantly. The only substance that could withstand that type of magic was silver."

Hermione looked from Gerrard to Karn, and had to remind herself that despite his manner, Gerrard was an illusion controlled by Karn. His voice may be his own, but his words came from Karn.

"So," continued Gerrard, "Urza built a magical probe to explore time and space. He poured his magic into it, and added unique devices to give it enough power to be useful. And in the end, his creation surpassed even him."

Again, Hermione looked at Karn. "You really are a golem, then? That's not just a name for something else?"

Karn's yellow eyes glanced up at her, before returning to the device on the table. "No, Miss Granger, I am a Silver Golem. The cornerstone of Urza's Legacy, and a planeswalker in my own right. There." Whatever else Karn was going to say was interrupted by a whirring from the device in front of him. Silver and brass legs stretched out and lifted off of the table, arms rotating as if for balance. A small triangular head swivelled around, taking in the room.

Focusing on the four-armed device, the metallic spider walked across the table to stand in front of it. When it began a chittering noise, as rapid as it was unintelligible, the four-armed device began to stir. It then replied in kind, and the conversation was underway.

"See?" Gerrard's voice sounded amused. "I told you he was a master artificer."

"You'll have to teach me," Hermione's quiet voice was clearly in awe of the achievement. Karn had created beings that could interact, seemingly with only a box of scraps.

"When this is all over, Miss Granger, I may do just that."

oOoOoOoOo

"He built what?"

Hermione sighed. "Robots, Ron. He took scrap metal Harry gave him and built mechanical creatures with it."

Ron continued lacing his boots, as he thought about that. "Why?"

"He seemed to think that we would need all of the help we can get." She looked at him evenly, keeping the worry out of her voice. "He's not wrong."

The silence stretched out for a moment, before tilted his head at her. "Something else is bothering you." It wasn't a question.

"I don't know, it might be nothing," her voice trailed off as Ron stood up and hugged her. She returned the hug, grateful for just a moment of comfort.

"Your guesses are better than most people's research, Hermione," he said, quietly. "What are you worried about?"

"When I was speaking with Karn," she began, "He showed me how he could make illusions that can interact with their environment." When Ron gave her a questioning look, she continued. "He created an image of someone he once knew, and that person took my hand. He lifted objects, and moved a chair around. It was so lifelike, Ron."

"Blimey," he said. "That could be dead useful,"

"Maybe," she agreed. "But Karn was controlling what the illusion did and said. Ron, he basically had a conversation with himself."

After a moment, he shrugged. "So?"

"So, Ronald, I think we need to be careful." Her eyes met his, and her intense gaze showed exactly how serious she was about this. "He's a living magical artifact who fought in a war - more than one, from the sound of it - and then spent centuries locked in a vault. And now, within a day of being freed, we're dragging him along with us into another battle." She sighed again. "I don't know why, I'm just worried."

Ron pulled her into another hug. "Don't worry, we'll be fine."

"I hope so," she replied.

"Hey, if Karn were going to be trouble, he wouldn't have helped us, right?" Hermione nodded in response, so Ron continued. "So, keep your eyes open and stay cautious, and we'll be fine." Ron decided to change the subject. "First things first, though. We've got to get them to Hogwarts, right? So how do we do that?"

"I don't know," Hermione admitted. "Can his portals go through wards?"

"He blew through those Goblin wards easily enough," Ron said, thoughtfully.

"If they can, then we can get into the castle before they know we're there." Hermione frowned. "But where do we go?"

The door to the ensuite opened, and Harry Potter stepped out. "We need allies," he said. "In and out of the castle."

"Bill will summon the order," said Ron. "Should we send a patronus?"

"No," replied Hermione. "But I might have a better idea, and we can kill two birds with one robot." Without hesitation, she stood up and left the bedroom. Harry and Ron shared a look at their friend's rapid departure.

oOoOoOoOo

Aberforth Dumbledore took a drink of his firewhiskey. Normally, he would not be drinking during the lunch hour, but seeing as his bar was completely empty, one drink would not kill him.

The death eaters were getting restless. Locking down the village was only the latest outrage, each worse than the last. The puppet ministry was trying to tighten its grip, and failing.

But it was all for naught if no one actually did anything!

His eyes caught a small piece of parchment, sitting on the bar. Had that been there before? Reaching over, he quickly read the green ink.

Sometime soon, I'd like to visit dear old Hogwarts. Perhaps you can point me in the right direction? Bill, an old colleague of your brother's, thought you might be able to help. If so, go into your back room and say that you agree. If not, say that you're closed and we'll find another way.

What in Merlin's name was this? Aberforth looked around, but saw no one. How did they get a note in without being seen? There were no enchantments on the parchment, so how would they hear him?

"This is stupid," he muttered. Not bothering to lock the bar, Aberforth walked to the back office and storeroom. The portrait of Ariana watched him with that sad smile, same as always. Looking up at the ceiling, he sighed.

"Whoever you are, I agree to help you." A quiet buzzing sound drew his attention, and he turned to see what looked like an insect hovering in the corner of the room. It seemed to be watching him intently. The sunlight coming in one window caught it as it moved, and the gleaming reflection reminded Aberforth of steel.

"Right, go on then," a voice said behind him. Spinning about, wand in hand, Aberforth Dumbledore saw a hole appearing in his wall. On the other side was Harry Potter. As he watched, Potter stepped through, followed by one of the Weasleys and another witch with brown hair. Behind them came a suit of armor such as he had never seen before.

The armor waved its hand, and the hole closed itself in a flash of red magic, leaving only an intact wall behind. When it turned to face him, Aberforth saw its glowing yellow eyes, and knew then that the creature was alive, somehow, and impossibly old.

Aberforth stared at the three teenagers and the magical suit of armor. Then he finished his drink in one go. Today would be a very long day.

oOoOoOoOo

To everyone's surprise, Neville Longbottom took the sight of Karn in stride. When asked about it, he simply shrugged. "This is my life now, I guess," he said.

Karn, for his part, had been quiet during the talk with Aberforth, and remained so during the long walk through the passageway. He had opened a window in the tavern, letting three of the little ornithopters fly away. Even before they reached the school, he could begin to get an idea of the challenge they faced.

The only sound in the passageway had been the heavy sound of Karn's footsteps, until Neville wordlessly silenced the golem's feet.

"Thank you, Neville," said Karn.

Neville didn't even miss a beat. "No problem, Mister Karn," he replied. It was another moment that showed Harry the confident leader Neville had become, for the nervous, unsure Neville of old would have stuttered and cringed at the golem's presence. Today, and probably for much of the last year, Neville was all business.

When they crossed the ward line, Karn froze in place. Turning, Harry saw that the golem's eyes had grown impossibly bright, as if he were flooded with power. "Karn?" he asked.

"Stand by," was the reply. It was whispered, as if Karn was in awe of what his eyes saw. "Remarkable," he said.

"What is it?" asked Harry, his wand out.

"The wards… I can interface with the castle." Karn's voice remained quiet, and his eyes had a faraway look to them. "Amazing." For the first time, Harry could hear true awe in the golem's deep voice.

After a few minutes, Karn's eyes returned to their regular glow. Briefly, he looked around, as if disoriented, before focusing on Harry.

"The magic of this place is incredibly complex," Karn said. "More so than anything I've seen before." He tilted his head, considering what he was sensing from the castle. "It's almost as if… I think she is welcoming us."

"She?" asked Neville.

A nod. "I cannot explain it without more time, but the impressions I am sensing seem indisputably feminine. She thinks of herself as…" again he paused. "She has an identity but it is unclear. Perhaps within the castle proper I will find more information for you."

"Good enough for me," said Harry. "Let's keep moving."

oOoOoOoOo

When the group arrived in the Room of Requirement, the gathered remains of the DA welcomed them with open arms. On every face, Harry saw renewed hope - which, in turn, gave him hope that they could win.

Karn let the others go in front of him, and as such entered the room largely unnoticed. Only a few of the refugees saw what looked like a suit of armor entering with the boy-who-lived, but they reasoned that the armor was just an added measure of protection.

Taking the opportunity, Karn placed his hand on a nearby wall, and took the measure of the castle's magic. It was not like the mana fields of Tolaria, nor the subtle but omnipresent magic of the city-world of Ravnica. Hogwarts was a castle first, he found, and over the centuries the magic of thousands of young witches and wizards had left its mark. Between the nearby ley lines - this world's equivalent of land-based mana - and the residue of the magicals who had passed through its corridors, Hogwarts had evolved into something… more. Something unique.

Once the battle was over, Karn very much looked forward to exploring the castle - and interacting with it.

For now, however, they had business. The castle could tell him where staff members were at any time, and from Harry he knew that the headmaster was a marked follower of the Dark Lord. An image of a black-cloaked man in an ornate office came to Karn's mind, and he gently probed the magic of the runic tattoo on the man's left arm.

The magic was hideous - at once simpler and much more pervasive than anything he had encountered before. It was almost like a slave bond, except that it left the wearer with free will, such as it was.

The castle informed him then that there were seven individuals in the castle who bore that mark. Six wizards and one witch. Two, a man and a woman, were in a classroom with a number of students; presumably they were professors. Three more were in a small room near the entrance hall, dining together. Guards, perhaps? The sixth was in the Headmaster's office, as Karn had already seen.

The seventh was in the Room of Requirement, standing next to Ron Weasley and his sister Ginny.

Karn turned to his companions, and saw a young red haired boy listening attentively to Harry and Ron telling their story. Other students were asking questions and telling their own stories, but the younger boy just gathered information.

It was not until the boy began to move toward an exit that Karn made a move of his own. Five paces from the door, Karn reached out his hand, and the boy fell to the floor as if he were a puppet with its strings cut. The other students were surprised when one of their own fell down, clearly stunned. They were then shocked when a suit of armor walked over to the fallen boy.

Harry, Ron, and Hermione had their wands out, covering not only the stunned form of someone they thought had been a second year Gryffindor, but the room as well. Months on the run had them taking no chances.

"What happened, Karn?" asked Harry.

Karn indicated the fallen boy. "Who is this wizard?"

After a moment, Neville answered. "Kevin O'Reilly, a second year. He found us a few days ago, and has been here ever since. He looked up at Karn. "Why?"

The palm of Karn's outstretched hand was glowing as he moved his fingers in an intricate pattern. "There is a chemical masking his appearance. I am unfamiliar with it."

"Polyjuice," said a grim Hermione. She looked at Neville and Ginny. "Do you brew potions here?"

Neville nodded slowly. "We have some hairs from Slytherins, which lets us polyjuice and enter the castle." He looked toward the back of the room, where another boy ran off to check and see if any potions were missing.

Harry, his wand still aimed at the unconscious boy, stepped next to Karn. He could sense the growing panic in the room, and wanted to help calm things down - but he needed to know what was happening first.

"What caught your attention?" he asked the golem.

Karn's yellow eyes remained fixed on the intruder. "The castle can tell me where the death eaters are located. She says there are seven in the castle. Two are guards, and four are professors." The silver golem nodded toward the boy at their feet. "And the seventh is on the floor in front of us."