Notes:

I will start by saying this is my first Harry Potter and Yu Yu Hakusho fanfic, let alone a cross between the two. The concept of this story has been one I've muddled over for years, and it was first sparked after reading a (now unfortunately abandoned) fanfic by the author Youko Koenma on this site called Thicker Than Water back in 2003. Many years and ideas later, this one would not leave me alone, so I thought 'Why the hell not?'

The timelines here will be slightly different, at least with YYH. The canon stories in both worlds take place only 2 years apart, but I wanted the 3 Kings Saga to be over by the time this story happened. For the sake of this story, the contents of the YYH anime have ended.

Also, this story first takes place in Harry's 4th year. Everything before that is canon, but this will not completely follow either the books or the movies. Tags will be added with subsequent chapters.

Enjoy!

Chapter 1: Observations

The roaring crowd of those awaiting the next competitor of the tournament was nothing new to Kurama. In fact, if he closed his eyes, he could easily imagine himself in the steep stands of the Dark or Makai Tournament, shoulder to shoulder with bloodthirsty demons, waiting to see the carnage of the next match unfold. The danger and potential for death was what drove them on, eager to see one of the next opponents fail, a primal desire to witness the weak fall and those with strength rise, all in the (somewhat) safe confines of the stands (if you don't count the stray attack or two that inevitably ended up going wide or missing its mark due to being dodged.) It all went hand in hand with being a denizen of the Makai.

However, he was not in the Makai, these were not demons, and this tournament did not involve those with martial prowess or the future leadership of an entire realm at stake. No, these were wizards, and they were cheering at the entertainment of four teenage wizards fighting for their lives against the first of three tasks that Kurama was rather sure they were, more than likely, woefully unprepared for.

And wizards described demons as barbaric.

Emerald eyes shrewdly studied the crowd once again. They'd already caught a pair of redheads taking bets earlier in what appeared to be a small suitcase, grins wide and heads bobbing in thanks as wizarding currency was exchanged. While many of the fans in the stands were students of the participating schools (along with several teachers and school leaders), he couldn't help but notice the large number of adults that had come to watch the ensuing spectacle. They were excited, smiling, even laughing.

Kurama was careful to hide his contempt. Just as he kept a tight lid on his youki while in this environment, so would he also keep any judgement from showing on his face. He understood the irony at the thought, given how he had participated in his fair share of tournaments whilst a teenager, along with Yusuke, Kuwabara, and Hiei (who hadn't been a teenager at the time, but that was beside the point.) However, since Kurama had actually been a more than millennia old kitsune before taking refuge in a human embryo, that didn't count. As for Yusuke and Kuwabara … well, they were used to violence, were rather good at fighting, and in fact sought it out. Plus there was Yusuke's status as a spirit detective, so it wasn't like he had much choice in the matter. Not to mention his eventual discovery of his own demonic heritage, but that was neither here nor there.

In any case, those had been demonic tournaments where death was bound to happen at some point, with demons who were (usually) decades to centuries old, if not older. No, this was a wizarding tournament, involving those who had just come of age, save for one participant.

Only centuries of focus and control kept him from shaking his head at his own thoughts, a carefully constructed mask always in place. Decades ago, if anyone had asked him his view on a teenage wizarding tournament, he would have promptly responded with either an 'I don't give a damn,' or 'Best if they killed each other.' Disdain didn't fully encompass demonkind's views of the wizarding world, and the feeling was mutual. Even during Kurama's reign as the Legendary Bandit, his personal thoughts on wizards and their uses were much like how one viewed toilet paper as facial tissue: okay in a pinch, subpar, and ultimately disposable. While his time as a human had softened him and given him both empathy and compassion, he still did not care much for wizardingkind, what with their supremacist views against everything nonhuman and for quite a few of them, nonwizard.

A pity they didn't even know their own history, or perhaps they refused to acknowledge it, which was all the more damning.

Now, even he knew not all of them were that way. Believing so would make him prejudiced, and that was something he would not allow himself to fall to, even though he and countless others from his past had a number of personal experiences with wizards to back up how they felt about them. Kurama had spent a fair amount of time convincing Hiei not all humans were bad, and the half koorime had even destroyed the Black Tape when he finally had it in his grasp. But Kurama still had a difficult time practicing what he preached when it came to the magic users. Their laws, their beliefs, what they taught their children at a young age … it all made it so difficult to find them remotely likable.

In fact, he still would not care to dally in the affairs of wizards, except for one small problem: this involved his family. Not his family as in his mother, Shiori, nor his stepfather nor stepbrother. No, it was directly connected to him, and his past.

It was still hard to believe what he'd been told when he was called to Koenma's office a few weeks ago. If he had been Yusuke, he would have expected it to partially be a joke from the child-like god, but Koenma never joked with Kurama. The evidence of the teenager's heritage had been there, mostly in the form of a file folder filled with documents, further corroborated by a handful of recordings, most of which showed the rather deplorable way in how a wizarding child had been failed by not only his institution, but also adults who should have been in control of the various situations that said child had to handle instead. Even further, he was still younger at the time than Yusuke was when he first became a spirit detective.

Even if his relations with the child hadn't been revealed to him, Kurama would have felt sympathy toward the boy anyway, even though he was a wizard. And that was before he found out about this ridiculous tournament.

But the problem extended even further than the fact the two were related. For the child's entire life, he had passed as entirely human. All scans, including magical, demonic and spiritual, would have said as such. But due to his ever increasing series of unfortunate events that plagued his life, that was changing. Given his status in the wizarding world, and the potential for his heritage to eventually be revealed, that made it Reikai's problem, and in turn, Kurama's.

He couldn't help but compare the situation to Yusuke and the revelation he was a Mazoku. But for him, the change from human to demon was sudden with his death. In this case, however, the change would be gradual, and there was still the possibility it would never fully reveal itself. Yet given the child's life so far, Kurama believed the latter scenario would be unlikely.

So now came the question on the minds of everyone in the know: how far had the boy progressed? And that was why Kurama currently found himself sitting in the stands of the first task of the Triwizard Tournament, wondering why on Earth three wizarding governments and schools of the world had decided to allow a group of teenage wizards to compete in what was historically a deadly competition.

And again, they called demons barbaric. Although Kurama took it as a good sign he didn't see any of the Grim Reapers in the vicinity.

He'd already witnessed three of the competitors tackle the first round, a rather arduous task (at least for someone of their skill level) of getting by a nesting dragon to grab a golden egg. Dragons were both dangerous and deadly at any given point in time, but a nesting mother even moreso. Kurama found it cruel to use a creature's instincts in this way, forcing a blind panic into the animal, making it believe its young were in danger, when really, this was all for sport. It was the 'for sport' aspect that rubbed Kurama the wrong way. Even during the height of his days in the Makai, he detested seeing creatures used like this. He may have been best with plants, but as a kitsune, he still had a tie to all nature, and that meant a rather unique connection to animals.

The first boy by the name of Cedric Diggory had tried to use wit, utilizing his abilities to change a rock into a dog to grab the dragon's attention whilst he snuck over to try and grab the egg. Not a bad plan, save for it failed near the end. Kurama's little understanding of magical healing techniques told him he should be fine, and would probably end up without even a burn scar for his troubles, even though dragon fire had grazed the side of his face.

The girl, Fleur Delacour, had tried a somewhat different approach, utilizing both charm and wit to lull the dragon into a trance and inevitably to sleep. He could easily sense she was not fully human, her energy minutely seeping youki, so small that not even the wizarding version of police (aurors, he believed) would have been able to detect it. He had heard from conversations in the crowd she was, in fact, a descendant of a Veela, and a rather recent descendant at that. It intrigued him that her crossbreeding didn't appear to bother the wizards, but then again, that was probably because the genetic attributes were rather dulled in the offspring, yielding only cosmetic effects of hair, skin and eyes, along with a lure to capture the male gaze and natural charm.

While Kurama may not be a fountain of knowledge when it came to magical creatures, he was very familiar with Veela. After all, they were the result of matings between male harpies and succubi, back when the barrier between Makai and Ningenkai didn't exist. Not that he expected wizards to know that, or perhaps the Veela had decided to not share the knowledge of their demonic heritage. After all, it would only cause them problems in the wizarding world, and he could not begrudge the creatures' desire to hide in plain sight to be able to survive and thrive in a world that would normally have detested them for what they truly were.

In any case, placing the dragon into a trance played well to her strengths. A little too well, unfortunately, given that the sleeping dragon was still able to breathe fire even in its stupor. Poor girl discovered that fact the hard way after the animal snored, shooting a jet of flame to catch her clothes on fire, although a quick wave of her wand doused it with water.

The third competitor, a rather well-muscled, athletic boy by the name of Viktor Krum, went a completely different route. In fact, it was one Kurama was sure either Yusuke or Kuwabara would have thought of. Simply hit the dragon in the eye. It certainly got the beast's attention, and kept it from attacking the teenager, but in its agony, the poor creature trampled half of the real eggs in its nest, destroying them.

Cruel indeed.

But now only one competitor was left to take the arena, and it was the one that had brought him here in the first place. A roar drew his attention to the end of the arena where a large, black dragon was brought in and chained to the ground, numerous spells holding her in place and to keep her from thrashing her spiked tail at the dragon keepers surrounding her. He heard its name from the announcers. A Hungarian Horntail. This was what a fourteen year old wizard was meant to face, when it took a team of fully trained wizards to keep it 'docile'. At this point, he didn't fight the desire to shake his head.

He still found it highly suspicious how a fourteen year old boy had managed to get entered in the tournament when rules clearly stated participants had to be seventeen. Not only that, but for a tournament that was supposed to only allow three competitors, a fourth had been picked. Kurama had no doubt magic would have been used to enforce those rules, but then again, wizards relied so much on magic for everything, and there were always workarounds. He'd heard from the crowd how many thought the boy had entered himself into the competition, some saying he did it for attention, but he sincerely doubted that. The dossier of what Koenma was able to provide of his previous three years at his institution made that highly unlikely. In fact, he was probably looking forward to a year free from schemes, dastardly plots and attention.

But it appeared as if someone or something wanted him to participate. Not even Koenma knew the reason behind it, only that he was forced into it, and it could potentially accelerate the issue at hand, depending on what was thrown at him. Whatever potential wizarding world dark plot that was, however, wasn't the main focus of Kurama's mind. He could get to that later if need be. Instead, all attention was directed at the entrance of the arena as a whistle blew, signaling the start of the task.

A lanky boy entered, small in stature for his age, with a mop of raven black hair and emerald green eyes hidden behind circular, wire rimmed glasses, his wand gripped tightly in his right hand. A gentle breeze caught the bangs of his hair, tousling it just enough to show a flash of the lightning bolt shaped scar that marked him as the Boy Who Lived.

Kurama frowned slightly. He was no stranger to what Harry Potter looked like after going through the footage Koenma had presented, but seeing the boy in person emphasized just how much younger he looked compared to his age. It appeared he hadn't hit a growth spurt yet, his height just below 135 centimeters. The glasses looked almost too big for his face, and if he looked closely enough, the bridge was held together by tape, a feature that made him pause in bemusement, much like it had when he first saw Koenma's footage. Wouldn't someone have used magic to fix that by now?

His eyes showed he was wary, the green orbs cautiously taking in his surroundings. Completely understandable since he was entering an arena with the goal of trying to outsmart an irate dragon. But a part of Kurama was also gratified to see they also held determination. That was the look of someone who had a plan. The kitsune had already intended to gauge the strength of his reiki, and perhaps, if it was close enough to the surface, his youki, but it seemed he would also get some insight to his mind and strategy as well.

His musings were quickly interrupted by an enraged roar. The boy ducked behind a boulder as the dragon's namesake slammed into the ground where Harry had dodged from. Flames followed suit, scorching the rock as the wizard crouched down behind it. The boy took a deep, calming breath, and strangely, he turned away from the rock that was between him and the dragon, and back towards the direction of the castle called Hogwarts. He raised his wand, and with a wave and a flick, he called out two words.

"Accio Firebolt!"

'Summon firebolt?' Kurama quickly translated the Latin, although his brow furrowed, having no clue what a firebolt was, and there was neither fire nor bolt of anything coming from the boy to the dragon. However, with Harry now having acted, the kitsune focused, searching for any hint of the reiki or youki he was looking for. So far all he felt was the child's magic, strong and focused, but that could change in an instant.

Harry once again dodge around a boulder to avoid the wrath of the dragon, the creature's chain straining to keep it from going too far outside its boundary. The Horntail had perched itself against a rock wall, staring down the boy in front of it. Green eyes stared back, a momentary flash of panic before he steeled himself and he was on the move again. This time he climbed an outcropping, stopping just below where his head would have poked up to be in the dragon's line of sight.

And that's when Kurama heard it. An almost silent fwoosh in the air. His own energy still focused on Harry, he looked up, surprised to see, of all things, a broomstick flying towards the arena. Looking back down, he could tell the second Harry had noticed the object, too. A flash of a grin swept his features, one that Kurama was quick to note was very similar to his own in his youko form. Harry launched himself up the rest of the outcropping, running both towards the edge and the dragon. As the creature opened its mouth to shoot fire, Harry leapt through the air, landing on the broomstick as it flew beneath him.

The second he gripped it and took off, Kurama felt a brief spike of reiki before it disappeared, the flash so quick, even he would have missed it if he hadn't been looking for it. It was the first bit of evidence he was searching for, even though he had to search through the boy's magic, or mahouki, to find it. But it had still been there.

He, along with the crowd, watched as Harry soared into the sky, his form growing ever smaller the higher he went. The boy slowly began to level out, before going into a steep dive, directly over the nest of eggs and where the dragon had returned to guard them. The creature's head followed the quick descent, along with everyone else in the crowd. There was no way the dragon would let him get near with a direct attack like this, not whilst in the line of actual fire. But it appeared Harry knew that too. He was baiting the dragon, and the animal followed it, releasing a torrent of fire Harry easily dodged, pulling out of the dive to avoid getting hit.

"Great Scott, he can fly!" cried the announcer over the shrieks and screams of the crowd. Kurama silently agreed, noting the boy was as comfortable in the air as he, himself was on the ground. There had been another spike, this time slowly building, when he dove towards the dragon and subsequently, when he dodged. Kitsune didn't hold much love for the air. That was normally outside their realm, so the talent for flying hadn't come from him, but those reflexes … perhaps. After all, energy and appearance wouldn't be the only things that would signal the emergence of his heritage.

The back and forth between the two continued for a few minutes as Harry attempted to gauge the dragon's reactions and how far it was willing to move from the nest now that he was in the air. He was able to dodge most of what the dragon threw at him, save for when its spiked tail grazed his shoulder. It didn't faze him in the slightest as he continued his careful, teasing onslaught. Each dive, every maneuver, all were accompanied by hints of reiki mixed with mahouki. At this point he was trying to get the dragon to rear up, perhaps take flight, anything to get it away from the nest so he could dive in to grab the golden egg. It was not a bad tactic, given Harry's ease in the air and natural ability on a broomstick. He was far more likely to succeed that way instead of on the ground.

As it were, he was flying just above the dragon, slowly floating higher with each pass, just out of reach of the dragon's flames. The creature was growing increasingly irritated, its patience growing thin. Harry had the right idea, until his plan fell to pieces.

With a mighty roar, instead of rearing up to try and grab the boy, it instead crouched down, extended its wings, and leapt up with its full weight. The chain snapped, allowing the creature to fly free. And its sights were set fully on Harry.

The crowd screamed. Kurama could see the boy mouth a curse before taking off, his plan to dive for the egg abandoned in lieu of being faced with several tonnes worth of fire breathing, irate dragon that was determined to devour the thing before her that had both annoyed her and threatened her young.

What followed was a cat and mouse game on a grand scale. Harry rocketed upwards, avoiding the crowd, away from the arena, and off towards Hogwarts, the dragon in hot pursuit. The two soon became dots on the horizon as they circled the castle, Harry doing his best to avoid the creature, the Horntail blasting fire in a near endless barrage. Even though they were too far away for Kurama to be able to sense anything from them at this distance, it was easy to tell Harry was very skilled at this. Almost unnaturally so, even by wizard standards. Most humans would panic at being chased by a dragon. Instead, Harry was evading it with grace and ease. Before long, Harry shot up the length of one of the towers and into the clouds, the dragon skimming the shingles of the roof as it followed.

Silence reigned, broken after a few seconds as murmurs began to rumble through the crowd.

It didn't last long.

A mighty screech sounded right above them, forcing everyone to look up. Harry erupted from the clouds in a near vertical dive straight for the nest. A flash of teeth followed by leathery wings dove after him, but too far behind to catch him, and he was too close to the nest for the creature to risk breathing fire. Harry laid flat against the Firebolt, gaining even more speed, eyes focused only on the golden egg below him.

As he approached the egg, that's when Kurama felt it. Not reiki. Not mahouki. Youki. Just a hint, but it was there in a brief, burning flash as the boy rotated in the dive, and came out of it over the egg, ending so that he was upside down over the object to grab it, righting himself with a quick barrel roll and shooting down to the other side of the arena.

Even though the crowd erupted in cheers, Harry neither slowed down nor dropped his guard, two things the kitsune approvingly noted. He still had a dragon after him, although it appeared help was on the way as several dragon keepers also took flight on their own brooms. It didn't take too much longer for the group to work in tandem to safely subdue the dragon without harming her, Harry acting as the dutiful mouse to keep her attention whilst the keepers utilized some form of spellwork on her.

Once back on the ground, Harry was quickly ushered away into the tent he first emerged from, a stern looking, if not slightly shaken, elderly witch steering him as he went. Harry had his egg in tow, his task now complete. But for Kurama, his had just begun.

The entire affair had lasted maybe no more than ten minutes, but it had been rather informational, or at least as informational as it could be without direct contact. Studying from afar only did so good, but it did yield a handful of revelations.

Even though Harry was unaware of it, he did have access to both his reiki and, more importantly, his youki. Rather, it was more like it was making itself known in instances of high stress and life or death scenarios, very much like how it spiked in young demons in the Makai as they went through their own forms of puberty. While all humans technically had the ability to access reiki if trained enough, wizards defaulted to mahouki, their very nature making them dependent on their magical cores. It was very rare for a wizard to call upon their reiki in even the most dire of situations, so for Harry's mahouki to be laced with reiki and even youki in brief spikes was very telling.

He ignored the announcement of Harry's scores, not really caring for the outcome in regards to the competition. However, Harry had reappeared at the edge of the arena to see what he had received, a red haired boy at his side. The name 'Ron' floated through his mind, remembering from the dossier he was one of Harry's closest friends.

With the area now calm, and the task over, Kurama hummed as a thought crossed his mind, deciding to test a theory. As much as he detested it as a toddler, he'd long since realized being reborn in a human body did have its advantages. One of those being he now had access to reiki instead of solely youki. It was that energy he focused on now, elevating its level while still keeping youki under the proverbial radar.

He didn't have to wait long to get his answer. Harry looked as if a shiver had run through him, the boy's head whipping around to see what had caused the subconscious disturbance. It never settled on a target though, and he looked both confused and perturbed.

Kurama's lips curled in a smile. Even though Harry wasn't able to pinpoint the location, he had felt the rise in spiritual energy. Most wizards required some form of magical device on their person to notify them of such things, including youki. The kitsune was certain Harry was too young to carry such a thing, which meant he now naturally had the ability.

He rose as the crowd began to disperse, the entertainment over, their hunger sated for now. He absently noted the second task, according to the announcer, was set several months away in February. Plenty of time for them to build up an appetite.

He made his way to the exit, and down the recently built walkway to find a secluded spot, passing the areas that had been designated for the wizarding forms of travel known as apparition and portkeys. For once he was thankful to be in a crowd full of wizards, the sheer number of them making it easy for him to disappear into the surrounding trees. Walking deep enough to insure he was both out of hearing and sight range, he pulled out a compact mirror and opened it. The reflective surface wavered before turning to black and white snow similar to a TV having signal trouble. Several seconds later, the image of Koenma in his toddler form sitting behind his desk appeared.

"Good to see the sheer amount of magic in the area doesn't interfere with Communication Mirrors," the god said with a nod, the pacifier in his mouth bobbing with every word. "I know anything electrical has a problem working in high magic areas, but I wasn't sure about any Spirit World devices. It's been ages since we've had to use them in such situations."

"You'll be seeing more use of them in the field of the magical world in the future," Kurama replied evenly, gently placing a lock of his red hair that had fallen out of place behind his ear.

"I take it my information was correct, then?"

"Yes. He is indeed changing, although I'm unsure of how quickly it is taking hold. He does have access to both reiki and youki, although it is subconscious. He's not even aware when it shows itself, and thankfully, it is still minute enough to not catch the attention of other wizards. Not only that, but his reflexes and intuition when it comes to dangerous situations are well above average for a human. However, I can't quite say if that is because of his heritage or not, considering most of that was evident whilst he was in the air on a broomstick."

"He was quite skilled," Koenma agreed. He had watched the entire affair from his office, although the visuals didn't relay information such as diagnostic values for reiki, youki, mahouki and the like. That was why it was best to have agents in the field to do more in-depth review. "It's rather surprising he's that comfortable on a broomstick. Then again, he does participate in that wizarding sport that's played on those devices."

"True, but to be well practiced enough to not only outpace but also out maneuver a dragon?"

"Touche," Koenma conceded. "But the fact remains he is slowly awakening. From what you've seen today, how far do you believe he is in the process?"

"Far enough to be able to sense my reiki, although I did have to raise it a little to see if he would react. He wasn't aware what it was though, only that he sensed something was off in his vicinity. I didn't dare risk trying my youki, given the environment," Kurama shook his head at the very thought. A large concentration of youki in a group full of wizards that also included wizarding government officials would have caused more than a stir. "However, I have no doubt this tournament will only accelerate it. With what you've shown me so far, he is well on his way to breaking the blood bonds that were passed down to him."

"Yes, surviving the killing curse as an infant insured that," Koenma heaved a sigh. He hated paperwork, and that situation was a never ending mountain of it for him. But this was also a personal concern for his most level headed Spirit Detective. "Do you think he will undergo the full change? Or will he simply inherit a number of attributes and skills?"

Kurama had already weighed the odds before contacting Koenma. Between what he knew from the dossier, what he'd already been told of Harry's ability to do the impossible, along with what little he saw today, he already had a feeling how this would turn out.

"I believe it's highly likely my grandson will become a kitsune. The question is when."

"I was afraid you'd say that." Another sigh from the god. "Not that I'm against you having a grandchild or that he'll eventually become a demon. I'm more concerned with who he is."

"And the fact he's a wizard," Kurama added. He would not hold that against Harry. He couldn't help what he was born as, much like Hiei couldn't help he was born as a half koorime. No, he'd withhold judgement until he could see if the boy held any of the wizarding world's prejudices to heart. If so … well, he was in for a rather rude awakening.

"Yes, that won't earn him any favors in either the wizarding world or the Makai after he completes the change." Koenama rested his elbows on the desk, clasping his hands. "He'll have to eventually be made aware of what is happening to him. No one else knows this is even in his blood. He needs to be prepared."

"I will make contact," Kurama assured him. "I had every intention of doing so." Even without the order from Reikai, Kurama would have found some way to approach Harry given his emerging abilities. Not only that, but he was his grandson. His time as a human had certainly rubbed off on him. Even though he'd never met the child before, or knew he existed until a few weeks ago, he still felt somewhat responsible for him. And if there was something his time in Ningenkai had taught him, it was the value of family, and he knew from the dossier Harry didn't have much family at all.

"It's a shame it's too late in the wizarding school year. We could have had you go undercover as a teacher at Hogwarts. You're too old to be a student, so even being a transfer wouldn't work," Koenma tapped a finger against his chin in thought, although Kurama was quick to intervene.

"I will not be going undercover as anything involving a wizard," he stated firmly. "My grandson may be one, but that does not mean I want to be around a large group of them on a near constant basis. Even I have my limits."

"Then what do you propose, Kurama?"

Said redhead shifted his gaze away from the Communication Mirror and to the surrounding trees, eyes searching for a sliver of a path through the foliage to show the castle beyond and the edge of another forest even further out.

"If Harry is to eventually become a kitsune, then it would probably be best if he became familiar with them. They aren't very common on this side of the world, so I doubt his curriculum even teaches about them, if they even touch upon youkai at all." Green orbs once again focused on the mirror in his hand. "And I have an idea how."