Timeline located at Harry Potter's Sixth Book, "Half Blood Prince", and after the "Dark Tournament" Saga of Yu Yu Hakusho.

Disclaimer: I do not own either Harry Potter or Yu Yu Hakusho. I only own the OC that will appear. And if you sued me for it, you'd probably only get a bunch of sketching, a worn-out laptop, and a PS2.

While reading this fic, you'll encounter: Death of minor/major characters, possible shonen-ai/slash/homosexuality, violence, swearing, and characters changing through the fic, thus becoming 'OoC', while still trying to keep them as canon as possible.

The Harry Potter Universe in this fic won't follow the events read in the Sixth Book. The Sequel planned for this fic, of course, WON'T follow the Seventh and last book of the Harry Potter Saga. The Yu Yu Hakusho series, in this fic, are also subject to adjustment.

Harry Potter and the Arc of Death

Chapter 1.- Down the Rabbit Hole

The weather that fell upon Europe, overwhelming and moody, proved to be a lot more difficult to handle than Japan's. Spring lingered only with the faintest scent of blooming flowers, and yet there were strong winds and looming dark clouds on the sky. The air felt moist even though no droplets of water had fallen yet, which told the two foreigners that this climate was quite common. They had gone to purchase warmer clothes at a local store when they arrived, as they had not been warned it would be so fresh. The jackets they had bought after changing their yen for England's currency served well enough to keep their bodies protected, but it didn't stop the red hair of one of the Japanese men from lashing about him, slapping his face whenever a wild breeze came by.

"I do hope this is as simple as Koenma promised it would be," the redhead said, tucking a strand of hair behind his ear as tightly as he could, concealing his annoyed state well enough that his partner felt free to complain.

"I want to go home now!" the other redhead (who had pompadour-styled hair) said loudly, earning a few more glances from the Londoners around. But they already looked their way when they spoke loud enough for them to hear, so it didn't really matter. Luckily, none of them seemed to understand Japanese, so Kuwabara could be as loud as he wanted about any matter. "Why couldn't the Detective or the Shrimp come to this one?"

Kurama smiled at the intentional lack of 'with you', or any phrase resembling it, in his friend's complaints. Kuwabara was not trying to insult Kurama's company; he was merely whining about wanting to go back home, where it was warmer and the sky clearer.

"Hiei's Jagan is as good as Koenma's database when we try finding people, but both tend to fail when we need to find objects or dimensional discontinuities. Your high sensibility should make it easier to find the false portal, and the rest we can leave to Koenma." There was a grunt as response, and Kurama resisted the temptation to shake his head.

He wasn't exactly ecstatic about coming to the mission either, but he had been lured into it with an offer he now thought dumb. The mere idea of visiting the only place on Earth with as much supernatural energy as Japan had prodded his curiosity. It had seemed like a good idea to come, back then.

Not right now, though.

The former thief had been called to Koenma's office in the Reikai merely a day ago, via Botan as this was an 'extremely important matter'. Or so said the leader sucking on a pacifier.

"Just a few moments ago," Koenma had stated grimly to the redheads, "a human disturbed an entrance to Reikai. We need to find and stabilize it before the raft widens the gate and creates a clear portal for humans to come through. As you both surely understand, we do not want the whole human population knowing what waits for them after they die." Plus, if the portal grew wide enough, the already-distorted dimension around it might create a second gateway to Makai, and then to the Meikai. Powerful demons would enter the human world, oblivious to the boundaries of Reikai's barrier, as this new portal would be raw and unrestrained.

They didn't need another Team Toguro in their hands. At least Kurama didn't, with his mother's wedding coming in a few months; he wanted to attend to it. What kind of perfect son would he be, otherwise?

Kurama didn't notice they had stopped walking until he realized his partner was behind glass and red metal. How careless of himself.

The redhead blinked inquiringly at his partner, who was fumbling and pressing buttons randomly at a phone. Giving a single look around (how funny; no one seemed to even glance their way now), Kurama pushed the door of the cabin open and stepped inside, leaving the entrance ajar behind him. The place was wide enough to hold three people, maybe four, comfortably enough.

"Kuwabara?" he called softly not to disturb the male, looking over his shoulder. He had to tip-toe slightly to achieve that: Kuwabara was quite tall, and the redhead just thanked being taller than a certain fire demon he knew.

"This is the entrance," Kuwabara said simply, as if that was a good enough answer for the knowledge-hungry fox demon behind him.

"Entrance to where?" Kurama pressed, more fascinated now than before. This seemed like an average cabin to him...

However, he never got his answer, as a monotone, female voice started chanting at them.

"Welcome to the Ministry of Magic. This entrance is currently unavailable— if you are a visitant, proceed through the route located eleven streets south. All employees must access the Ministry through their designed entry. Every visitant will be asked to go through wand verification. Thank you, have a nice day."

"Ministry?" Kurama repeated, sensing the energy vibrations from the telephone now that he knew what to look for. Everything was knit so close together here… he'd have to ask Kuwabara or Genkai for help with toning his senses. If he were Youko right now, he would have caught it along with Kuwabara. But since he was human, and it took so much training to become aware of beings other than himself, he had only focused on training his senses to human-like life (demons and humans) and plants, mostly. Sensing objects affected by reiki should be useful, though. Very useful, specially in wizard populations that depended so much on such objects.

"The Ministry of Magic," Kuwabara offered, once more pressing buttons. "My mother works here."

"Your mother?" Kurama repeated. He felt a bit dumb all of a sudden: normally, it was him answering everything. It was a bit refreshing to have new knowledge to absorb, though. "Isn't she at Japan?"

"Well, yes, my stepmother. My mother, though... Well, it's complicated," the male said awkwardly. "I'll tell you later, okay?"

"You don't need to," Kurama assured, stepping forward when he noticed Kazuma looked like he would hit the phone if it didn't do whatever he was trying to coax it to do. "Can we enter through here?"

"I think so. I was never really interested in this kind of thing... But if this is out of service, then we don't get verified, right?"

"If they're not expecting people to enter through here, then I don't think they are paying much attention to this entrance," Kurama said with a nod. He was rather pleased with Kuwabara's sharpness. He'd never thought it would be bad to have him as partner, but everyone knew he wasn't the smartest of the group, and he was too noble towards everyone. Too explosive. Now, though, he knew that he wouldn't go mad if he did get stuck with him in a mission longer than this one. "I think I can unlock this..."

"I don't think it's going to be a normal lock..." Kuwabara pointed out.

A sly smile took over Kurama's lips and his eyes narrowed slightly, a hand going to his hair to extract a single little seed of a kind of thin vine. "A lock is a lock. And a bandit can pick any lock." He bent slightly, letting the plant grow smoothly and hastily on his outstretched hand. He'd just have to use youki more than physical pushing to break it.

"I'll just keep watch, then," Kuwabara decided with a small nod, hands in pockets as he looked around.

Like I need it, Kurama thought, not cruelly but amusedly. And it seemed that, still, no one looked their way. How ironic. How could anyone walking past them not turn to stare at a pair of Asian teenagers, who seemed to think a phone worked by sticking a plant into it? It was safe to assume that the cabin itself was enhanced with reiki.

He shook his head slightly, focusing on the task at hand. The thin vine slipped into the opening where coins came out from. Or, at least, where he assumed they came from: this was a very odd-styled phone cabin. When he found a hollow space inside, he decided he was either completely right, or very wrong. He focused on the feeling of barriers… they weren't quite solid, but they still made his vines advance more slowly. Just pushing at the right ones should work...

"Whoa!" Kuwabara cried as the floor of the cabin started moving. Kurama pulled his vine away, making it shrink into a seed once more and sticking it into his hair, just before the street disappeared and they went under the ground. After a few moments, what was in front of them was a narrow hallway. An empty hallway, thankfully.

So the Ministry was underground.

"I was expecting something more magical," Kurama admitted as he stepped off the red metal floor, onto the brown welcome carpet, and advanced efficiently down the marble floor. He soon heard Kuwabara's stumbling steps following him, and focused on locating people nearby. There were a few, from the soft steps he heard outside... but it was early in the morning, so perhaps not as much as there could be. That was the best they could ask for.

"The portal is down here?" Kuwabara nodded his head, getting past his amazement in order to do so. Obviously, he hadn't been here before. There was knowing it existed, and being in it. "Do you know the exact location?"

"I know the direction," Kuwabara said, moving his head towards it. Which was downwards, and somewhere to the right.

Kurama couldn't quite see any stairs, so he guessed they would have to come out of their pretty, safe, empty hallway. I had a feeling Koenma was lying, the redhead though dryly.

Finding a dimensional discontinuity in the Ningenkai was easy. Humans tended to ignore anything paranormal. They blinded their eyes, deafened their ears, and muted the voice of their own souls. It was not a completely irreversible state (look at Kuwabara!), but it was one that worked for them rather than against them in these kind of missions. It lessened the imminent damage that would be done, if humans did not wander and stumble into the portal. "Wizard" humans, though, were not as much monkeys as their neglecting siblings. While they wouldn't be able to sense reiki or youki unless trained (which they had in common with ordinary humans), they had power.

This was a "get through a government base full of paranoid and armed monkeys without being discovered" mission. They couldn't let the wizards know why they were here, so going through 'verification' was not an option: the guards would ask too many questions. Like, what were two young Japanese men doing at the Ministry of Magic of Europe, when they obviously didn't speak English fluently.

"We'll need to get there discretely, then," Kurama finally said, advancing to the only door of the corridor, right at the end of the hallway. "Follow me, try not to fall behind."

He opened the door carefully, and he surveyed the situation: they were in a better position than he could have hoped for. Not many guards. Of course, this was an average government building, so there shouldn't be a lot to begin with: they would all be at the entrances and important areas. But there were neither a lot of guards, nor a lot of wizards. There were big gaps of time between the persons that walked down this huge entrance with black marble, and to the far side, Kurama could see a golden statue. They could hide behind that if they had any trouble.

"Come on," he said, looking back at Kuwabara once to check he was prepared, before going out of the room. Swiftly, Kurama went through most of the entrance, going at a just-slightly-faster-than-human speed (he had Kuwabara as partner, not Hiei) and reaching the statue just in time to hide from a wizard that passed by.

The redhead mostly ignored the statue he and Kuwabara were hiding behind (arrogant wizards; AS IF every demon and derived creature looked up to them...). Their main mission right now was to find a way to go further down – he hoped there were floors lower than this one, because it would be really hard to close a torn portal that was a mere hole in some cavern several feet bellow them.

"Are those elevators?" Kuwabara asked in a murmur, making the fox turn his head to look at the way he was pointing his finger. Indeed, at the end of the hallway was a pair of metal doors leading into small compartments... like the ones you found in hotels and really tall buildings.

"Seems that way."

I'm still waiting for something more magical, he reproached mentally as they went over to the elevators. A quick roll-and-duck-behind-a-pillar when someone came out of an elevator, and both redheads went into the small compartment, the door closing behind them softly. A small, annoying tone started to play out of nowhere -- Spontaneous music. It's better, but not quite my idea of magic – and Kuwabara pressed a random number from the panel right next to the metal doors.

"Do you know where we're going?" Kurama asked, leaning against a wall as the elevator started to move.

"I hope so," Kuwabara said, frowning a bit. Kuwabara pressed the button with the number 'two' in it, but when they started to move upwards, he quickly pressed 'three'. They were still going up. Kurama counted four floors upwards just as Kuwabara went to press the fifth, and pressed the button 'eight' to get back to where they were. Only two floors were under them. He tried with nine, and Kuwabara nodded his approval once the elevator stopped and the doors opened.

Kurama went out with him, looking around. Empty. They were either having a lot of luck, or this was a trap. And, somehow, he doubted the last. Not even Botan knew about the mission: just Kurama, Kuwabara, and Koenma. So perhaps they were being lucky. And by now, he could too sense the horrid chaos that only an accidental portal could cause.

"So we check where exactly it is and then leave?" Kuwabara asked silently, as they headed for the door at the end of the hallway. It had an alluring air to it that made Kurama both uneasy and eager to reach it.

"Yes, but I'd like to take a look at it first," Kurama said. A small report of the damage so far wouldn't hurt, and he did want to know just how 'urgent' this actually was.

He pushed the dark door open, and both human and demon hybrid stepped in. Imagine their surprise when the room around them started to spin. Kuwabara had his spirit sword in hand and Kurama a rose whip ready by the time it stopped. They remained in a defensive stance until they decided nothing was going to attack them, and that they couldn't hear anyone nearby. They kept their weapons out, though, just in case.

Kuwabara pushed open the door to the portal (try as they might to daze them, wizards couldn't hide energy), and they cautiously proceed into the room.

Well... now, this is magical.

In the middle of the room, several rows of stairs downwards, was a single stone arc, within which there was a clear veil made of the sacred energy of Reikai. Or at least that was how it seemed to Kurama. It swayed back and forth with nonexistent air, and from it, faint whispering could be heard... many of the voices were alien to the fox, though some he recognized.

"Youko... Run, escape..." and that one made him shiver. But now he knew what this was.

And he frowned at the knowledge.

"Why is this down here?" he murmured, as they went down the steps. The air seemed to thicken as they advanced, and it was slightly harder to breathe. Nothing deadly, though: the veil was only struggling, trying to tear itself open at the same time it tried to tug itself closed. Apparently, tearing was winning, for the way the cloth lashed about.

The whispering became stronger, and Kurama turned quickly to Kuwabara.

"Don't listen," he said. It was easy to notice, for the bewildered look in his face, that he too could hear the whispers. He didn't know if Kuwabara had anyone he would want to follow, but he wasn't going to take the risk of letting him even think about going past the veil. The human hastily nodded when he heard the kitsune's stern tone, and Kurama returned his gaze to the veil.

This was wrong… why was this here? And how come Koenma hadn't found it yet?

"Ehh… Kurama?" His eyes turned to Kuwabara, to find him pointing at something just past the veil.

"Kuwabara, anything you see or hear coming from the portal is not real," he said, looking back to the veil. His last statement faltered as he spotted something not in the veil, but clearly behind it. He would have mistaken it for a silver fox (such as himself in his past life), if it weren't so wide and much rougher-looking... No. This was not a fox. It was a dog.

A big, silver-colored dog, that was sitting right behind the veil. Watching them with uncanny black eyes, which seemed as deep as the black fire that consumed body and soul. But this black was much more compassionate.

"I'm pretty sure that dog is real," Kuwabara said.

Not two seconds after the male said that, the huge dog ran forward, going right through the veil without being sucked in by it, and past the pair of detectives. Its sides brushed lightly against the guys, and Kurama froze, Kuwabara yelping. They turned around and, without need of words, ran after the dog, the air clotting further behind them.

"How can that thing be the rupture?" Kuwabara asked. "Is it a demon?"

"No, but it's not much better; it's causing the raft to widen! We need to take it to Koenma," Kurama said, as they ran back upstairs. The dog went right through the door, and they entered the spinning room a moment later. Kurama frowned impatiently as the doors started moving, and pushed the door to his right open to keep chasing the animal.

The creature jumped, and they had to loose precious time by going up through the elevator. Kurama tapped the heel of his shoe against the carpeted floor as the now-annoying music filled the room, and he sprinted behind Kuwabara when the doors opened. It didn't take long to spot the glowing body of the canine, running boldly through the wide hallway, the one with the golden statue in it.

There were people walking around right then... but they had to catch that thing. Screw the cover.

They turned and went into a hallway, turning again at some point and continuing for a while. The damn thing was fast! And with people walking in the Ministry, turning and following them with their gazes until they got out of sight, they couldn't go much faster. A small stumble, and then Kuwabara lunged. His arms wrapped around the white dog's neck, despite Kurama's yell encouraging otherwise. Surprisingly (for Kurama), the dog's body seemed to be quite solid, and Kuwabara managed to halt it's advance.

Kurama stopped next to the pair, panting softly – playing human teenager as perfectly as always – and watching the dog struggle lightly, but finally sit down and settle, knowing it wouldn't escape from the human's strong arms.

Well, that had not been as easy as they expected it to be, but at least it was ov—

"Hey, you two." Three basic words of English, that Kurama could definitely understand.

Kuwabara groaned softly, as both teenagers turned to face a stern-looking man that was waving a stick around in a 'come here' motion. Kurama turned to Kuwabara, frowning a bit.

"I only know a passable amount of English… I'm not fluent, though." He had never really expected to leave Japan during his lifetime. He was knowledgeable in various Demon Languages and Japanese, commonly used at the upper Makai for better cover in the Land of the Rising Sun. The barrier was weaker in those specific islands. A demon wouldn't bother learning French or Italian if the humans in the place they came out at talked Japanese.

"I'll take care of it," Kuwabara said with a small nod.

Kurama didn't question his decision, and took the other's place at holding the dog down. He just knelt down by it, though, a hand firmly on the back of his neck. He watched as Kuwabara went over to the man, and started talking in heavily accented, rough English. It was better than Kurama's, though. He'd remember to practice more when he got back home. It wouldn't hurt to learn more human languages.

It seemed he had a lot to do once he went back to Japan.

He sighed softly, turning his attention to the dog, who was panting and looking completely normal right then. For a moment, it's eyes turned to stare at the green orbs fixed on him. It was everything it needed to do, though, for Kurama to learn that 'it' was intelligent. Not that he hadn't suspected so already.

"What are you, anyway…" he murmured, shifting his grip.

In the small fraction of second that his hand left the dog's skin, the animal ran off, neatly cutting off the small root of trust Kurama had placed on him. There went the stereotyped loyalty towards the "man's best friend", right out of the window.

He stood up and went after the dog, calling a "Be right back!" as he went past Kuwabara and the man questioning him. He briefly heard yelling, probably directed at him, and as he turned the corner, he could hear steps coming behind him. They wouldn't think he was escaping or anything, would they...?

"...transferring prisoners to their jail!" he heard from Kuwabara, whose voice was less concerned than the guard's.

Oh. So there were few people here because of that? Well, it wasn't like they could harm Kurama: his reflexes were as sharp as ever, as the tournament had just been held a few weeks ago.

Still, he hadn't expected that, in the next turn, the dog would come right back at him, tackling him to the ground. It promptly hid behind Kurama, baring his fangs at something in front of them. The mildly thrown-off redhead turned to the front, just in time to spot a demon running through the hallway in front of him, jets of light flying past him, but never hitting the target.

The demon rose a wooden stick swiftly, and cried "Protego!" in a deep, powerful voice. A barrier with an unnatural green glow to it appeared, swallowing and spitting back most of the jets of light going his way. And as he turned to continue his escape, a certain small movement of his neck gave Kurama his name.

They had met before, when Kurama was still Youko. And this was the last place where he would have expected to find him again. His name slipped from the redhead's lips before he could think twice of it. He was that sure of his unconscious call.

"Athanatos."

Gray eyes turned to him for less than two seconds, and they narrowed briefly. The stick was pointed Kurama's way.

"Avada—" A loud crash, and the male forgot his spell-casting in order to escape from the shower of lights that came through the broken barrier.

The fox just sat there, perplexed, as Kuwabara reached him, the guard leaving them to join the persecution. Kuwabara helped him up hastily, tugging him back towards the lifts they had come from. The dog seemed to be quite willingly following, now. Just in case, Kurama grew a thorn-less vine to use as leash on his neck. He was not about to let the "animal" run off again.

"Come on. My mother works at the Second Floor, I think," he muttered. Getting help from one of the workers might get them out of trouble. Kuwabara turned to Kurama, who just nodded. The human still seemed at a loss, though, if not worried. "What was that back there?"

Kurama shook his head, frowning at the recent memory.

"It was just an omen, Kuwabara. And I don't think it was a good one."

A/N

"It was not a completely irreversible state (look at Kuwabara!)" : Why didn't I mention Yuusuke as well? He died, and his powers unlocked that way. He was 'deaf, mute, and blind' before the accident. Kuwabara was naturally sensitive, and had to work hard to get his reiki to be strong enough to be used as weapon. I'm not saying Yuusuke didn't work hard (he's struggled as hard as the other characters through the series, if not harder), but he got a bit of help.

"...pressed the button with the number 'two' in it, but when they started to move upwards..." : They started at the Atrium. Which is the Eight floor. The Department of Mysteries is at the Ninth.

"A big, silver-colored dog..." :So, you might have your suspicions about this. If you're wondering why it's silver and not other color, it will be explained later on.

"...Land of the Rising Sun..." : Japan is sometimes referred to with this name. Don't start saying that "it's not japan, it's phoenix" or anything. I'm not trying to annoy anyone, it's just a fact: Japan is sometimes referred to as the Land of the Rising Sun, because Japan means "sun-origin".