A Call to Arms

I don't own Danny Phantom or Harry Potter

Chapter 1: A New World

The landing from the portal was less than gentle but Danny had experience with rough landings. The thick green grass he rolled onto was like a mattress compared to being thrown into concrete and asphalt, as what usually happened during ghost fights.

Brushing off bits of moss, grass, and dirt, Danny made a slow turn and surveyed the area for threats. He was in a forest glade idealic in its bright streams of sunlight, thick carpet of moss and grass, and ancient trees with dark gnarled limbs. Bird song echoed around him after the initial shock of his sudden appearance wore off. When nothing attacked or threatened him, Danny turned to the portal. It hung almost invisible a few yards above the ground, high enough so nothing but birds could wander through by accident, but low enough to get to with ease. The only clue that it was even there was a slight rippling of the air and if you looked at just the right angle you could see the faintest green shimmer bleeding through from the Ghost Zone.

Danny set down his pack and pulled out his portal gun, a less hostile, smaller, and more versatile version of his parents' ecto-bazooka. Unlike the bazooka, the portal gun was geared entirely around detecting, measuring, and hopefully reopening portals into the Ghost Zone. Due to its reduced size, more the size of handheld vacuum cleaner than a full sized bazooka, its ability to reopen a portal depended entirely on latent energy from the original portal. Which was why getting an accurate reading on when the portal would close was so important. He'd already taken one reading before coming through from the Ghost Zone, now a second reading was to confirm the first.

Danny leveled the gun, for lack of a better term, to the invisible portal above and measured the decay rate for the energy. In theory, it should give him an approximate time when the portal would close. The display screen flickered, threatening to shut to off. Danny frowned and hit the side of the device with familiar force. He wasn't quite at the level of technical knowledge as his parents or Tucker, but to be fair he'd mostly only had to piece together bits from his parents' other inventions. He was familiar enough with their work to accomplish that. Still, there was something in the display that kept shorting out and he really needed to get it fixed. The display gave one last flicker and popped up bright again. He had around seventy hours from now give or take a few before the portal closed. Danny set the timer on his watch, then marked the portal's location on the gun's internal map.

Pausing for the portal reading also gave Danny a chance to make sure he wasn't followed. While unlikely, it was possible a random ghost could follow him and cause havoc in this world. More likely than that, he'd have to check that a certain ghost puppy with a protective streak didn't track Danny through the Zone. Since the beginning of Danny's expeditions, Cujo had taken to following Danny even if that meant following through various portals to play with his favorite halfa.

It was simultaneously touching and annoying. Danny had always wanted a puppy but his parents' many dangerous experiments going on in the house made it difficult to own any pet, much less one as inquisitive as a puppy. However, Cujo had terrible timing and could just as easily cause problems wherever he went, case and point: Valarie aka the Red Huntress. This time, though, the enthusiastic puppy seemed to be somewhere else.

When Cujo failed to make an appearance after several minutes, Danny figured he was in the clear by way of unexpected tag-alongs. He stowed his equipment, placing all electronics out of sight at the bottom of his pack, and set off flying invisible to a good height to see the area. Seventy hours was plenty of time to take a look around and see some sights.

Danny had started his self imposed mission to explore the Ghost Zone only a couple months previously. At just over eighteen years old and drowning in boredom at the local community college he'd managed to get into despite his suffering grade average, Danny needed a pass time that did not involve homework. The ghosts had largely died down from their constant harassment of the human world during the first couple years of Danny's powers and there were more ghost hunters than ever before so the town hardly needed him anymore. When it came down to choosing between homework, contemplating his largely blank plan for the future, or exploring the Ghost Zone on an increasingly regular basis, Danny didn't really consider it a contest.

The woods stretched out for miles in either direction, thick, green, and lush. It had the packed density associate with ancient forests which meant at the very least Danny wasn't in the Midwest anymore. Off in the distance there seemed to be a building, rising up over the trees. Danny smiled, he'd started these expeditions to go exploring, discover new things, so he pointed himself toward the building and shot off at a quick pace.

As Danny neared the structure, his curiosity turned into delight. He had found a castle. Even if he had tried he wouldn't have been able to suppress the wide excited smile spreading across his face. Everyone loved a good castle.

Danny flew lower, dipping down so he could weave between the spires and their fluttering banners. This was a no-kidding, real life, castle, he said to himself grinning as broad as ever. It didn't look like one of those touristy places, no ticketing booths or outdoor attractions. There didn't even seem to be any modern conveniences, no modifications to the outside for gas, electricity, indoor plumbing. Perhaps, the portal he'd gone through not only went to a different location spatially, but also lead to a different time. It was completely possible after all and Danny had experienced the Ghost Zone or another ghost's ability to jump between times on more than one occasion.

Diving down into one of the walls, Danny phased into the building to get a better look. The halls looked just as old, but still used. They were filled with carpets and paintings, suits of armor and display cases line all alone the walls. Flying around the corridors, Danny came out to a large stairwell with multiple stair cases crisscrossing to different floors.

Initially, he was going to fly past and continue his exploration, but then Danny skidded to a stop mid-air as he realized something about the staircases. Looking, then looking away, closing and rubbing his eyes, then looking back did not change the fact that the stair cases were moving, gliding along to attach and disconnect from other stair cases and platforms with the smooth rhythm of a silent symphony. Glancing around once again, Danny realized it was not just the staircases that were moving when they weren't supposed to, the portraits were also moving, or at least their inhabitants were. Danny floated closer to one large painting and observed the subject fast asleep with his chest rising and falling with each gentle puff of breath. Other portraits were not so subtle, some of them were looking at Danny openly, whispering behind their hands. A couple even left their frames only to appear in another to whisper to the occupants in that painting.

Danny stared, eyes wide. These paintings weren't digital images, they were actual canvas works. Observing other aspects of the castle, including partially living suits of armor, dustpans that moved on their own, and mirrors that spoke to him as he went past, Danny could only come to one conclusion. This was not just a castle, this was a MAGIC castle.

Danny's parents would have scoffed at the notion of magic, like what you found in story books, but Danny had seen far too many examples of magic, real magic, from his dealings with ghosts and the Ghost Zone. Finding something like this wasn't that much of a surprise.

Danny flew through the corridors more excited than ever, but also a little confused. The castle was huge, fully furnished, and also recently inhabited, by all evidence, yet there wasn't a soul to be seen. It was only late afternoon, possibly early evening, according to the slanting position of the sun outside, a noticeable time difference from Danny's own world. It would be nighttime by now back home.

As soon as the thought crossed his mind, a red jet of energy shot out of nowhere knocking Danny to the floor. He spun around throwing up a shield just in time to block another jet of red light as he frantically searched for his attacker. Danny cursed himself for his own carelessness, in his glee at finding a magical castle and the lack of visible people roaming the halls he'd allowed his guard and his invisibility to drop.

Catching sight of the attacker, Danny rolled to the side taking himself out of view of the figure on the staircase. A couple jets of red light splashed against the stone wall just as Danny moved behind the cover. Fading invisible and intangible, Danny floated up and out to get a better look at who attacked him. The person was a man, with black hair and a strange combination of normal clothes underneath a set of elaborate robes.

"Here!" the man called, his accent definitely British. "I found the intruder over here!"

Moments later, footsteps heralded several more people joining the man on the stairs. Cautiously and with skill Danny could only associate with intimate familiarity with the battlefield, the man and his new companions moved down the stairs. They held short wooden sticks out in front of them like weapons, probably magic wands, Danny thought, and failed to suppress another grin despite the dangerous situation.

Until one of the magicians, upon discovering Danny wasn't just around the corner cast some sort of spell that moved out like an expanding dome from the person and forced Danny out of invisibility.

"Ack!" Danny yelped and dodged back up the stairs being chased by more red jets of light. Really, magic was getting old, very fast.

Danny skidded to a stop when another group in similar robes came charging up the hall toward him. "Can't we just talk about this?" Danny asked, hands up with palms out.

"We don't negotiate with You-Know-Who's dark creatures," one of the people spat before aiming another attack at Danny.

Danny dodged, phasing through a stair case and putting the moving ramp of stone between himself and the group of magicians.

"No I don't know! Who are you talking about?" Danny cried. He'd had enough experience with first encounters with people to tell him there were two ways he could handle this to get the best outcome. One would be to talk these people down, the other would be to fly away and not look back. Right now, option number two seemed his best bet and he prepared to go invisible and fly up through the ceiling.

"Hold your fire!" a new voice called. Danny looked up and saw an old man with a very long beard striding toward them. He wore fancy robes like the others and had a new group of people trailing behind him. "Everyone remain calm," the man said, as the others parted to let him through.

"Just for the record, I'm not the one shooting at people," Danny said, hands held up in innocence. "Sorry about the trespassing thing, I probably should have knocked, but there's no need to get so hostile."

"That will entirely depend on your actions and reasons for being here, I'm afraid," the old man said. "If I may, who and what are you?"

Danny grinned. That was a better reaction than most of the ones he received from ghost hunters. Most of them didn't even bother introducing themselves much less ask Danny to introduce himself, though it had been a long time since Danny had run into a ghost hunter from his world that hadn't heard of Danny Phantom. "My name is Danny," he said with a slight wave, "And I happen to be a ghost."

Several of the robed figures scoffed. "You are no ghost," the first man that had attacked him said with a sneer.

"Yes, I am," Danny countered, folding his arms over his chest. "Besides, how would you know? How many ghosts have you met before?"

"Hundreds," the man said, with a tilt of his chin, "The castle is infected with them."

"Really?" Danny asked looking around the walls speculatively. His ghost sense hadn't gone off once since he'd entered the castle. "Not sure I believe you…" Danny narrowed his eyes.

The man sputtered but the old man raised a hand to cut off whatever retort was coming. "You'll have to forgive my friend here, Danny. We've never encountered a ghost resembling yourself. Almost all of our apparitions lack color and most lack the ability to interact with the physical world."

Danny turned that thought over in his head. The description that the old man gave implied those ghosts, if they were ghosts had never set foot in the Ghost Zone and therefore had never interacted with a regular supply of ectoplasm. Putting the matter aside, he could deal with exceptionally weak ghosts at a later date, Danny turned to the old man. "You know I introduced myself, but you never did. Mind telling me where I am, too? Since I really, honestly don't know."

"Yes, how rude of me," the old man said with a benign smile. "My name is Albus Dumbledore and you are currently in Hogwarts School of Witchcraft and Wizardry of which I am Headmaster. It is a pleasure to meet you."

It was the benign smile that did it. Danny glanced around at all the others gathered on the hallway balcony and stairwell. To the last man they had their wands out and pointed toward Danny, all except this Albus Dumbledore. Nobody reacted to a strange, possibly dangerous creature with a benign smile and no visible means to defend themselves unless they knew that could handle whatever came at them with ease. Of all the people facing him at the moment, Albus Dumbledore was the one Danny had to be careful of if an earnest fight did break out.

"So this is a magic school?" Danny asked, ill concealed glee leaking into his voice. This was so much better than homework for his algebra class.

Dumbledore's smile grew wider at hearing Danny's tone and the brief glance around the stairwell and its moving staircases. "I take it you've never encountered wizards before, then?" It was not a question.

"Well, I've encountered magic," Danny shrugged returning his attention to the magicians trying to subtly surround him. "But nothing like this." He eyed the many wands still point in his direction, pointedly looking at the magicians moving behind him. "Not sure if it's a good thing or a bad thing, though."

Dumbledore glanced around at his companions as well, noting their battle ready state. "Put your wands down. I'm sure if this young man wished to harm us, he would have had multiple opportunities to do so, considering his abilities."

Slowly the group lowered their wands, but kept the wooden instruments to hand. Danny mentally shrugged. It was as good as he was going to get for the time being.

"Perhaps we could continue this conversation in a more comfortable setting." Dumbledore gestured up the hallway in the direction from which he had appeared. "I would be very interested to know how you found yourself here."

Danny scanned the crowd around them. Most of the other magicians still had their wands in their hands. Only a few looked like they really took this Dumbledore guy to his word about Danny and had put the wands away. The wariness was understandable, though, considering the magicians were gambling a little on Danny's harmless intentions. Dumbledore didn't seem too concerned. Still, the thought of putting himself in a confined area with multiple possible aggressors went against Danny's instincts.

"I would also be willing to answer any questions you may have about our school," Dumbledore said as added incentive, a smile hovering around his lips and a twinkle in his eye.

Danny bit his lip. Ignoring the old magician's obvious attempt to cajole him, he did have some questions about magic, living people's magic at least. It seemed similar to but still different from ghost magic. As long as they didn't try to trap Danny, and Danny didn't tell them too many details, exchanging questions and answers seemed alright. If nothing else it'd be a great story to tell Jazz, Sam, and Tucker, having a chat with a modern version of Merlin in a magical castle with a bunch of real living magicians.

Jazz, Sam, and Tucker would probably beat him black and blue for his recklessness. They already thought he was taking too many chances exploring the Ghost Zone alone. The fact that he was having a hard time taking these magicians and their pointy sticks seriously, pointed to there being some truth to that concern. Maybe he wouldn't tell them after all.

Danny shrugged, simultaneously oozing bravado and a carefree attitude, "Sure, no promises on answering your questions though."

"Excellent," Dumbledore beamed and turned back up the hallway, not bothering to check if Danny was following.

Danny did follow, maintaining intangibility, as the rest of the magicians gave him a wide birth. Murmured comments between the magicians followed Danny and he could feel their stares ranging from curious to suspicious on his back. He kept a mild expression on his face, trying to look as non-threatening as possible. Up ahead he could hear one of the others whispering loudly to Dumbledore.

"Are you sure this is wise?" It was the man who had initially attacked Danny to begin with, the one who didn't believe Danny was a ghost. "We have no idea what that thing is. What if it's one of You-Know-Who's minions?"

Dumbledore replied in a normal voice, loud enough for Danny and many of the others to hear. "My dear Marcus, while I may not know much about our guest. I can say with near certainty that he is not one of Voldemort's followers."

"So a ghost, huh?" a voice snagged Danny's attention, drawing his gaze down to a man several years older than Danny walking closer to him than the others. He had messy black hair and glasses. A red headed woman walked on the other side of him, their hands clasped as she eyed Danny with caution. She was pregnant, Danny realized, seeing her abdomen bulging from beneath her dress.

"Yup," Danny said ignoring the man's clear disbelief. "It doesn't matter if you don't believe me, doesn't change the facts."

"Hmm," the man responded observing Danny from the corner of his eye. "James Potter," he said by way of introduction. "And this is my wife, Lily." He held up her hand, beaming with pride.

"Danny Phantom," Danny replied with a grin offering his hand.

James stopped halting the progress of their group down the hall and stared at it a moment. The others immediately surrounding them eyed the interaction with acute interest. More than one hand tightened around their wand. Don't screw this up, Danny thought to himself. Far too often it was minor interactions like this that determined whether he was a friend or target.

"James…" Lily breathed, her grip tightening on their claps hands.

James fixed a deliberate smile on his face and slowly took Danny's offered hand giving it a quick shake. His eyes widened in surprise when his hand made contact with Danny's and he stared at his own hand for a moment after the handshake was over.

"Your ghosts must be extremely weak if they can't even become tangible," Danny commented with a chuckle. That's right, Danny thought, just keep being the friendly weird ghost, don't give them any reason to think you're dangerous and you'll get through this no problem.

"Depends on what you're definition of the term 'ghost' is, I guess," James said, eyeing Danny again like he was some impossible puzzle. "Maybe you're not really a ghost but just think you are?"

Danny scoffed. "And what're the chances of you being mistaken about the fact that you're human?" He spun around when someone poked his leg. "Hey!"

The one poking him, another man several years older than Danny and with straight black hair, about shoulder length, and a mustache, froze before retracting his hand like a dog caught doing something they weren't allowed.

"You're cold like a ghost," the man said, brows raised and lacking the intense amount of wariness the others maintained around Danny.

"Because that's what I am, a ghost," Danny said with a roll of his eyes. He flew after the retreating back of Dumbledore, now a dozen yards ahead of them. Though, the old man had paused to observe the small interaction.

They eventually stopped at a statue which leapt aside when Dumbledore murmured something close to it. Behind the statue was a revolving staircase which Dumbledore rode up followed by the others in their group. For the sake of space, Danny righted himself and stood on the stairs like the others, although the only ones who would get close to him were James, the man that had poked him, Lily, and another heavily scarred man in shabby clothes.

The stair case took them up to an open door which led to a circular office filled with books, whirling and spinning trinkets, and delicate machines. Danny floated several feet off the ground again, noting the window as a possible escape if things went sideways. Two staircases led down along either side of the wall, curving with the room. On one end, between the two staircases sat an ornate desk and behind that was a large perch with a bright gold and scarlet bird.

Danny hoped the bird was a pet phoenix. That would make the story all the more incredible and therefore unbelievable to his friends. They'd be so jealous, especially Sam.

"Is that a phoenix?" Danny asked pointing at the bird, eyes bright, even before everyone managed to cram into the room.

Dumbledore's grin grew even wider, if possible. "Why yes, my boy. This is Fawkes."

He probably shouldn't press his luck, but Danny couldn't resist. "Can I pet him? Or maybe hold him?"

Several of the people below him scoffed. Danny glanced around the group, a number of the older folks frowning in disapproval. One woman in emerald robes had a frown that spoke extensively of exactly how she felt about Danny's undignified suggestion of petting and holding a phoenix like a common parrot.

Dumbledore merely chuckled, "Perhaps when we're finished."

The room didn't look big enough to accommodate everyone, but it did, even if it was a little cramp. Dumbledore glanced around at the crowd. "I think it might be best if we avoided overwhelming our guest all at once. Professors, you do have duties you should be attending to, am I correct?"

Numerous groans went up around the room, but almost half the people turned and filed down the stairs. The man with dark hair that took such offense to Danny's presence glared one last time before storming out of the office.

"Never fear," Dumbledore cheerfully called after them, "I shall inform you of any important developments." The promise seemed to do nothing to raise the other man's spirits as he slammed the door behind him.

When the last teacher filtered through the door only a relatively small group of people remained including the four that had been near Danny on the staircase, another extremely large man that Danny would bet was a real giant, and a grizzly man with paranoid buggy eyes that scowled at Danny.

"Well, we're not missing this for all the magic in the world," the man who had been poking Danny's leg folded his arms and leaned against the desk, "I don't care what excuse you come up with to get rid of us."

"I wouldn't presume to try," Dumbledore said, he snapped his fingers and a tray with cups of hot tea appeared on the desk making Danny startled back higher into the air. "But some of them are still untested and we must be careful."

The grizzly man in the corner nodded his head approvingly, but turned down the tea offered to him. The others in the room each took a cup, trying to pretend this was a normal social get together.

Danny noticed there wasn't a cup for himself, no doubt in line with his claim of being a ghost. If the ghosts here were as weak as it appeared, they wouldn't be able to eat. Danny didn't bother correcting the headmaster, wanting to get a better feel for these people before accepting any food or drink they had to offer. His friends might think he had grown reckless, but he wasn't stupid. That one incident with the deranged zoo keeper looking for new exhibits had taught him at least one thing.

"So," Dumbledore said ignoring his own cup and with all the airs of a friendly host welcoming a new friend. His eyes seemed to twinkle twice as much close up. "What brings you to our school, Danny?"

"I'm just exploring," Danny said, maintaining his carefree attitude, though part of him didn't like being in the enclosed room with this many people. He was beginning to question his own judgment on this. Maybe he should have just run from the start. "I was out looking around and stumbled upon your castle and... Well, it's hard to resist taking a look inside a magic castle."

Dumbldore smiled, "Yes, I can understand. I myself sometimes take the long route to get here through the woods or over the lake just to get a sight of her again. So that was all? Just out to explore the world?"

"It's better than homework," Danny smiled. Yup he was just a harmless student, who happened to also be a ghost, nothing to worry about here, no-sir-ree.

"So you're a student then? What are you studying?" Dumbledore asked. Now, he reminded Danny of a visit to one of those homes where the old people asked all sorts of mundane questions about the lives of young people.

"Not quite sure yet," Danny shrugged. "Do you really teach magic here? Teach people how to be magicians?"

Dumbledore chuckled, like an old grandfather. He didn't fool Danny for one moment. This guy was dangerous. "We do teach magic, but the correct terms are witch and wizard. Magician is more closely associated with the Muggle profession of creating illusions and misdirection."

"Muggle?" Danny asked, trying to keep his eyes on the old man. The room had too many interesting things to examine.

"It's our term for non-magic people," Dumbledore said, then with a wider smile, "If you're curious about anything in the room, feel free to ask."

Danny forced his wandering attention on the conversation, but fully intending to pepper the old man with questions once it was his turn. "So magic…it's something you've either got or haven't got?" Danny clarified with a frown. He had always thought anyone could wield magic, so long as they had the correct artifact or knowledge.

Dumbledore nodded, "A person is either born with the ability to use magic, or they are not. The extent of their ability is both a matter of natural talent and determination to learn. Make no mistake, a person with a great deal of natural talent will not necessarily become more skilled than someone willing to push themselves."

Danny checked his other impressions of the old man. Dumbledore was definitely a school teacher. "That's what my teacher used to say," Danny muttered thinking of Mr. Lancer.

Dumbledore smiled in return, then continued the conversation. "I take it from your accent that you are from America. How did you get here precisely?"

Danny hesitated a moment. This was where it got tricky. He didn't want to give these magi... wizards more information than was safe. After all, who knows what the wrong wizard entering into the Ghost Zone could do? Then Danny would have to be the one to clean up the mess. "I'm not sure I want to say, exactly," Danny said, crossing his arms over his chest. "After all, you guys did attack me on first sight. I know I was trespassing but those weren't warning shots being fired at me back there, I know the difference."

Dumbledore looked down clasping his hands in front of him. "I do apologize for the actions of my staff. We, our world, is currently experiencing troubling times and many people are on edge."

"Oh?" Danny asked, thinking back to the accusation of being connected to someone. "Does this have anything to do with that guy the other guy mention? Voldewort?"

James Potter and the other one that had poked Danny's leg snorted, then laughed outright, only to be smacked by the red headed woman, Lily.

"What? It's funny!" James said, flinching away from the woman.

"This is serious," Lily said, with a deep frown.

"No, I'm Sirius," the man with the longer black hair grinned only to get smacked again.

"Voldemort," Dumbledore corrected, bringing everyone back to focus on the conversation. "And yes. It does have something to do with him. I take it you've never heard of him."

Danny shook his head, then grimaced. This was becoming more complicated and Danny had a sinking feeling it would lead to Danny's involvement more than he was willing to commit. Perhaps it was better to come clean, in a vague sort of way. "Look, I'm not actually from your world. I've been exploring a pocket dimension that has portals opening up to any number of worlds. My own world doesn't have magic like you do here, at least I've never seen it. Plus all of our ghosts are like me. Trust me, they're two completely different places."

"Excellent," Dumbledore beamed. "You must have come quite a way. You're more than welcome to stay the night." Several of the people in the room spun to stare at the old headmaster.

Danny looked at the old man with a narrowed gaze. "In return for what?"

"Nothing," Dumbledore said with an innocent smile, "except, perhaps, for the chance to interact with a being from another dimension. Much magical speculation has gone into the possibility of other worlds, dimensions, planes of existence, yet we have had no proof of the possibility until now."

"You're curious," Danny summed up, sitting back in the air, arms crossed over his chest.

"Yes," Dumbledore nodded, "I am immensely curious."

Well, Danny could certainly relate to that. He glanced at his watch, pulling up the timer counting down to when the portal would destabilize. He still had another sixty hours, probably, and he didn't really need to be back to school for another couple of days. No one would miss him. Plus, when was the next time he'd get a chance to explore an honest to goodness magic castle? "Alright," he nodded slowly, "I'll stick around for a day or two as long as you let me pet the phoenix."

TBC…

A/N: This is a shortish story (three chapters) I wrote last year and only just now got around to editing and publishing. I wasn't sure if I should post it before or after National Novel Writing Month, but since the rest of the year will probably be very busy for me, it's going up now. It's already complete and updates will be weekly.

Please read and review and let me know what you think.