A/N: After seeing some good KHR and Yu Yu Hakusho crossovers (all with a female Tsuna for some reason) I decided to take a crack at it. If you guys couldn't tell, I love supernatural AUs. *sweat drops*

And bakeneko are very powerful. Basically they can shapeshift, use fireballs and reanimate the dead as puppets. That is one cat you don't want to piss off.

Disclaimer: I don't own Katekyo Hitman Reborn! or Yu Yu Hakusho.

Heart of the Beasts

Tsuna ran as far as his tiny legs could carry him, tears streaming down his face. His day started out horrible with one of the older boys tearing up a picture of his only friend, a cat with twin tails. Then when they read aloud what they all wanted to be when they grew up, everyone laughed when he said he wanted to be a robot. At one point he meant he wanted to pilot a robot like in anime, but now he wished he could become emotionless. Maybe then all the taunting and jeering wouldn't hurt.

He ran into the forest and heard a familiar purr, his gloomy expression brightening when he saw his friend. He sat down on a fallen tree, allowing the cat to rub its face against his leg. "At least someone other than Mama cares about me." Tsuna sniffed as the cat looked up at him with intelligent green eyes. "Your kindness is wasted on humans."

Tsuna froze, looking around to see where the voice was coming from. "Down here my child." The voice said in amusement, Tsuna's stunned expression causing the bakeneko to chuckle. "You...you can talk?" Tsuna asks in awe, rubbing its chin. He giggled as the demon purred affectionately, eyes closed in content.

"You are a very rare breed of human boy, rare indeed. While your spirit fire is shackled, you still retain your Sight. Spirits and demons alike pay their debts when it is due." The bakeneko states, looking up at Tsuna. "But you don't owe me anything! I don't mind feeding you and I like playing with you."

A growl emanated from the base of the demon's throat. "It is easy to take kindness for granted. Were any of those children kind when they belittled your dreams? Were they kind when they would throw stones and laugh at you?" The bakeneko demands. "No." Tsuna says quietly, his voice cracking. The bakeneko's twin tails flicked back and forth, showing its irritation.

"Your caretaker is lost within their own mind and her husband constantly absent. We demons may be beasts but even we ensure our children are happy and healthy. One day you will break and I do not want to see it happen." Its voice had been livid but it softened slightly. "But if I leave, won't Mama be lonely?" Tsuna sniffed, the bakeneko scoffed. "I am capable of many things young one. Deception is one of my many gifts." With this the bakeneko held their head up proudly.

XoXoXoXoXo

Tsuna had stubbornly stayed with his mother, unable to believe the sweet woman could ever forget him. Slowly Nana began to forget to pick Tsuna up from school and he had to run away from bullies to get home. Nana would be in the kitchen, blinking in surprise when the door would be slammed shut by Tsuna.

That wasn't the end of it, sometimes she would forget his portion of food or lock him out of the house. She was starting to forget her own son, little by little.

Currently Tsuna was sitting on the swings, watching the clouds lazily go across the sky. "For what it's worth, I am sorry about your mother." The bakeneko says, jumping onto his lap. "Can I at least know your name?" Tsuna asks. The demon blinked. "I have no name." "How about Kuro?" "That is acceptable." The newly named demon says, not really caring.

Kuro lead Tsuna deep into the forest until they arrived to a portal. The only items Tsuna had with him were a blanket, his stuffed lion and a change of clothes. "Where are we going?" Tsuna asks, Kuro jumped into his arms. "A certain group of demons owe me a favor. Should any of them try to harm you the consequences shall be dire." Kuro states, rubbing its face against Tsuna's chest.

The portal lead to the Makai, Tsuna shivered as he took in their surroundings. The sky was a strange mix of purple and grey, and the plants looked like they were barely clinging to life. There was a giant castle with small hooded demons gathered around it, yellow eyes and fangs visible when they turned to Tsuna. "We found a tasty treat." One of the demons cackled, the demons moving as one to overwhelm the terrified boy.

Kuro hissed, its tails glowing as several fire orbs appeared, setting their attackers alight. "None of you vermin shall touch this child!" Kuro snarled. A giant stone demon watched the exchange in amusement, it had been many decades since they had visitors. And having a human that wasn't eaten alive was interesting as well. "I'm sure Byakko will be thrilled to have a new play thing." Genbu chuckled, fazing through the wall.

Kuro and Tsuna reached the Gate of Betrayal, Tsuna found it odd that there wasn't a door or anything to keep people out. In the back of his head, something was telling him there was a trap of some kind. It was the same feeling that told him where to run while being chased by bullies. "Why do you hesitate?" Kuro asks curiously. "Something doesn't feel right. Don't places like this have traps?"

Kuro purred. "That is correct. The entrance has a ceiling that lowers to crush intruders. We merely need to outrun it." Kuro stated. For a kid that couldn't run without constantly tripping, this was horrible news.

Tsuna watched as Kuro grew to the size of a large cat, resembling a panther. Kuro lowered itself to the ground. "Hang on and don't let go." Kuro states. Tsuma's screams echoed as he clung to Kuro's fur. "Hieeee!"

10 years later...

Yusuke and his group stood outside the Gate of Betrayal, preparing to face the Saint Beasts. "It's been a while since we've had visitors other than Skull and Kuro." A voice says in amusement, coming from a figure sitting on the wall. He looked human with the exception of gold eyes.

He jumped down from the two story height, using his flames to slow his descent. He was short and had the sort of energy that put people at ease. "You were just going to run in guns blazing, weren't you?" He crossed his arms, looking at them expectantly.

"We don't have time for this kid, there are lives at stake!" Kuwabara exclaims. Tsuna raised an eyebrow. "My brothers wouldn't have taken such drastic actions if the Spirit World took their request seriously. Do you know why your boss sent you?" Tsuna asks. Hiei scoffed. "They are detectives in name only." Tsuna snickered. "Tell you what. Instead of you all attempting to kill my brothers, leaving me without a family," Tsuna shot them all a look. "We can talk this over without anyone dying."

Yusuke looked disappointed at not being able to fight, but entering the castle on the kid's terms was an easier option. Tsuna then whistled, calling a spirit beast that had the same flames as his own. "Gao?" The lion cub tilted its head, waiting for Tsuna to speak. "Make sure that eye bastard doesn't try to squash us like bugs. I honestly don't know why they keep it around." Tsuna grumbles. "Gao!" Natsu nodded in agreement before going to guard the switch.

"So...uh, you are human right?" Kuwabara asks, Tsuna nodded. "I am but I find it easier to interact with demons. The people in my town either ignored my existence or tormented me for their own amusement. Even my own mother forgot about me." He says nonchalantly, Kuwabara and Yusuke winced. Tsuna did look like the sort of kid that would be a bully magnet.

"It's not like I hate all of humanity though, there were just more bad than good where I grew up. Just like there's good and bad demons." Tsuna explains. "But aren't the Saint Beasts evil?" Kuwabara asks, Tsuna raised an eyebrow. "If it was the Saint Beasts from a decade ago, they wouldn't hesitate to gut you like fish. How would you feel if you were forced to stay in the same castle for centuries?"

XoXoXoXoXo

Tsuna lead them through the maze of rooms, at one point they even went through a room where the floor was lava and they had to jump across different platforms. "Dude, what the hell!" Kuwabara exclaims, Tsuna smiled sheepishly. "There was a huge misunderstanding when I wanted to play the floor is lava as a kid. Natsu seems to like it though." The lion cub already jumped in and was swimming through it. "Gao~"

There was also a room that was completely covered in ice, everyone except Hiei and Tsuna shivering in the cold. "Alright first it was lava, now it's a freezer. You think they'd make up their minds!" Kuwabara complains. "This is Seiryuu's training room. Byakko usually goes to the lava room whenever he pisses him off. If you couldn't tell Seiryuu is an ice demon." Tsuna says bluntly.

Finally they reached a tower, making Tsuna's guests groan. "Now are you glad you decided not to run in head first?" Tsuna asks. "I might just want to kill them for putting so many damn obstacles in this place. And now we're getting a cardio workout? And I thought school was bad!" Tsuna just gave him a look of confusion. "Your school is a fortress filled with demons?" Tsuna asks.

"Are you kidding? That would be way less boring! How long have you been in this place anyways?" Yusuke asks, Tsuna looked thoughtful. "I've been here since I was seven so... a decade I think." There was an awkward silence before Yusuke started to laugh. "Dude, I would pay to watch four demons forced to raise a brat!" The communication compact in Yusuke's pocket started to vibrate and he was suddenly reminded that he was there on a mission.

"Yusuke, have you gotten the whistle yet?" Botan pants, hitting a possessed human with a baseball bat. "We're about to meet one of the big guys right now. You think that you could patch us in to Koenma when we do?" Yusuke asks, Botan's eyes widened in surprise. "I suppose I could. But why?" She asks. "We might not be getting the full story."

They entered a room with a throne and a large screen on the wall. Suzaku was there as well as the other three Saint Beasts. Genbu resembled a turtle and was made entirely of stone. Byakko looked like a giant werecat. The two that looked more human was Suzaku and Seiryuu. "I see you've safely escorted our guests Tsunayoshi." The blond demon states, patting Tsuna on the head affectionately. "Tch. We couldn't have roughed them up, not even a little?" Byakko asks, sounding dejected.

"Maybe later. We pulled this stunt to get the Spirit World's attention and now we finally have it. All we request is a meeting with Koenma and we'll call off the attack."

XoXoXoXoXo

Apparently Koenma hadn't gotten the memo that the Saint Beasts had gone through a drastic change over the past decade. If he hadn't seen Tsunayoshi happy and healthy on the screen himself he would have assumed the human was a slave or food. Koenma hadn't even read the request they had sent, he raised an eyebrow when he finally read it over. "Why the sudden interest in the human world?" He asks, Seiryuu stepped forward. "We have taught young Tsunayoshi to defend himself but he still belongs with the humans. We wish to send him back and be able to visit occasionally."

Koenma looked over Tsuna's file briefly, his eyes narrowing. "It may take a bit of convincing but it appears that my father may owe your ancestor a favor. With the heavy burden on your family, you'll need all the help you can get." Koenma says bluntly.