This is my first crossover of two universes I've never wrote about before. So please tell me if the characters are OOC so I can correct them in the future. Now, the story is mostly about the Organization XIII, and that includes Roxas as well. In the Kingdom Hearts' timeline I don't know when it is and frankly I don't care, but in Harry Potter it happens in the fourth year. It was initially the fifth year but I changed my mind.

Let's begin!

Unexpected

Chapter 1

…

The Castle

The abandoned city spread like a dark river beneath the shadow of the white wonderful castle. The pale rays of the heart shaped moon reflected on its impeccable walls, making it shine in through the blackness of the night.

There was silence in The World That Never Was, with the exception of the ghostly steps belonging to the figure walking on the pitch black streets. The hooded man continued to walk until he reached the brink of the forest before going in.

He followed the path for a while and stopped when a shadow loomed over him. Looking up, the man saw the person he was supposed to meet sitting on a higher branch of a tree.

"What took you so long?" a feminine voice was heard through the death silence. The figure on the branch jumped down in front of the man. The woman's coat was black just as the man's but had two stripes of white on both sides of the zipper that met on the back forming an 'x'.

"Nothing important!" the man replied, an image of a drunken Luxord and Xigbar appearing in his mind.

Almost reading his thoughts, the woman sighed putting her hands on her hips. "Is everything ready?"

"Yes. When will we start?" he asked in a deep strong voice.

"In three days."

The man nodded as the woman disappeared in a black portal. Turning back, the hooded man walked back toward the city, stopping to watch the castle dominating the town with the moon shining on the sky above.

The next day…

A yawn coming from the Melodious Nocturne broke the silence of the corridor as he strode along the Cloaked Schemer toward the dormitories. Mumbling under his breath incoherent things about the new mission, Demyx threw his arms behind his head and started humming to himself.

Beside him, Zexion was ignoring the music maniac and continued to read his book. It wasn't that hard as he got used with reading while everyone around him acted like the noisy idiots they were. The both stopped when two familiar voices reached their ears.

"I'm telling you, this will be the coolest thing in the world!"

"And I'm telling, it won't be that cool when he finds out it was you!"

"He'll forget about it by the time we come back! Chill Rox!"

"Axel, did you forget about the last time? You were stuck in a block of ice for two days!"

"God! That ice was really hard to melt!"

Roxas sighed crossing his arms. "You have such a talent for getting into trouble!" Axel only rolled his eyes and waved at the duo waiting for them.

"Hey Axel, Roxas!" greeted Demyx.

In the next second he was all over Axel trying to find out who was the victim of which prank the red haired pulled this time. Axel smiled and leaned toward his best friend. "See, I like his enthusiasm better than yours!"

"And I like you better in one piece!" he replied.

Sensing this conversation was going to last, Zexion decided to bring up their new mission. Demyx groaned, both because he had to go and because, Axel hadn't told him his latest scheme.

Now, back on the track, the group left their home through a Corridor of Darkness and winded up in a creepy looking forest. The withered ground was covered by the giant roots of the trees, that soared toward the sky with their thick leafless branches forming a dome that stopped the light from touching the earth.

"Are we in the right place?" yelped Demyx, his voice waving as he watched the shadows lurking through the endless mass of grey trees. "Please tell me we're in the wrong world."

"Calm down!" spoke Roxas in a reassuring way. "We just have to get out of this forest."

A loud clap startled the three teens and they swiftly took a battle stance except from Demyx who jumped behind Axel for cover. Trying to find the source of the noise, the boys spotted Zexion standing on a root, holding his now closed book.

"If you are done talking, we should move." Axel snorted but followed nonetheless the blue haired Nobody. After what seemed like forever for some of them, the forest started to thin out revealing an old castle. It wasn't as big as the Castle That Never Was but it did give a strong vibe of magic.

The group strode until they got to a big lake. That's when they heard barks and yells coming from a lone cottage near the forest. Pulling their hoods on, the four Nobodies ran to the place to see a big man hitting some black and blue creatures while his dog was barking his head off at them.

"Heartless!" breathed Axel when they stopped.

"We should help him!" shouted Roxas summoning Oathkeeper and Oblivion in his hands. Axel followed suit calling with a burst of flames his two chakrams.

The two of them jumped in front of the man, startling him and making the Heartless back off. Axel twirled the two rings in his hands before throwing them ablaze at the enemies and slashing them to pieces. At the same time Roxas swung his keyblades destroying them while Zexion and Demyx went to the man. In less than five minutes the Heartless were gone and the two Nobodies dismissed their weapons and walked to the others.

Clearing his throat, the man towering over them spoke. "Name's Hagrid, the Keeper of Keys and Grounds at Hogwarts! Thank yeh for helpin' me out. Those little devils keep comin' back, I tell yeh! So, who're you?"

"We're nobody of importance!" spoke Zexion before anyone else could say something. "Say, do you know where more of them are?"

Hagrid blinked at the sudden change of subject."Well…I dunno, they may be in the Forbidden Forest, but yeh should talk to Dumbledore, he may know summat!"

Hagrid watched the four hooded teens exchanging looks before nodding and the same person spoke. "Where is he?"

The half giant smiled and answered. "Come with me." He started walking toward the castle and entered the courtyard while watching the four strangers looking all around them. Pushing the entrance doors wide open, Hagrid leaded them through a maze of staircases and corridors.

"So Hagrid, how old is this castle?" asked Roxas watching another door vanishing and leaving behind a plain wall.

"Very old!" barked the man making the younger Nobody almost jump out of his coat. "Built by the most powerful wizards!"

"Are you a wizard?" asked Axel raising his eyebrows even if it couldn't be seen from under his hood.

"Yeah, I am…or was! Wha' 'bout yeh? Aren' yeh too?"

"We can do magic but we never really th-"

"Hey guys! The paintings are moving!" squealed Demyx interrupting Zexion while pointing excited at a portrait of a fat man eating.

The man seemed insulted and annoyed at the same time. "Humph! Of course I can move you dimwit!" Demyx looked taken aback as the others were trying hard not to burst into laughter behind him.

"Moving on!" screamed Hagrid dissipating the tension in the air. After another 500 tunnels, Hagrid arrived at a stone gargoyle and whispered something in its ear. To everyone's surprise, except from Zexion's, the statue nodded and moved revealing a staircase going up.

Hagrid gestured them to come and they soon found themselves in front of a door. The Keeper of Keys, knocked politely and shortly after a voice from the inside invited them in. The room was circular, decorated with all kinds of silver machines that they bet Vexen would give all Luxord's munny for. There were also many portraits that seemed to watch them carefully, and a personal library that made Zexion drooled from just looking.

Behind a desk, sat an old man dressed in some blue robes with a matching pointed hat, long white beard and hair and half moon spectacles. Next to him stood a beautiful bird with red and golden feathers sleeping soundlessly.

"Hagrid, what may I help you with?" he asked kindly. The old man took a glance at the ones behind the half-giant and added. "And who are they?"

Hagrid cleared his throat and told the headmaster. "They've help me get rid of those creature that started appearing around the castle lately."

"Oh, is that so?" his eyes twinkled as he conjured four chairs with his wand. "Please sit down, and thank you Hagrid!"

The half-giant, nodded and left the room as the four Nobodies took a seat in front of the old man.

"I am Professor Albus Percival Wulfric Brian Dumbledore," - Demyx wow-ed silently under his hood. "Headmaster of Hogwarts, School of Witchcrafts and Wizardry. Thank you for helping out Hagrid. May I ask who you are firstly?"

"We prefer to not reveal our names. We are here only to get rid of the Heartless!" answered Axel crossing his arms over his chest.

Dumbledore frowned. "Heartless?"

"Yes…the um, black weird looking things…" said Demyx. "…even thought they could be other colors too."

The wizard nodded and asked again. "And what exactly are those Heartless?"

This time Zexion spoke. "When a human's heart is consumed by darkness, he transforms into a heartless while at the same time a Nobody is born. The empty shell without a heart that remains from the human."

"I see! And you are here to destroy them!" the four of them nodded while Dumbledore closed his eyes and opened them ten seconds later. "Well, the Heartless started popping out last week and there seems to be a lot of them around the castle. And with the school starting tomorrow, I fear for my students." He finished looking at each one of them.

"So, you want us to stick around and protect the school, right?" asked Roxas watching his teammates. "Lots of people means lots of hearts and that is…"

"…and that is a feast for the Heartless!" finished Demyx. "Come on guys! It could be fun!" he paused and turned to the headmaster. "That means we're gonna get a place to stay and enough food, right?"

"Well of course! We have enough rooms and galore of food." Dumbledore chuckled as the boy turned excited to the others.

Axel and Roxas liked the idea and Zexion also gave a hesitant nod but not before adding. "Just to be clear! We will stay but not for the whole school year. We'll leave after we've done our job!"

Dumbledore smiled, crossing his fingers in front of his face and watching them from above them, the same twinkle coming back in his blue eyes. "Very well! But I must tell you something about this year! Hogwarts has been chosen to house the Triwizard Tournament, a competition between the three most prestigious schools of magic. And also, I would like you to keep an eye and three certain students."

"That doesn't mean we're going to babysit them right?"

"Of course not! Just take care they won't get in any trouble; they always seem to! Oh…and before we make our deal, I would like you know I'm not associating with persons whom faces or names I do not know."

"I was sure we're gonna get to this eventually." spoke Zexion pulling down his hood and revealing a teen with light blue hair that covered his right eye while the other was a bright aqua shade. Dumbledore watched the other three teens pulling off their hoods, and then he turned to the blue haired one.

"I am Zexion." He said. "And these idiots are Axel…" he pointed to the tallest of them, a boy with spiky red hair that reached his shoulders, and whom vibrant green eyes threw daggers at his teammate. He also had a purple marking that resembled a tear under each eye. "…Demyx…" he moved his hand to his left and to a boy shorter than Axel, but taller than him, with sparkling green eyes and dirty-blond hair arranged in a mullet and with several bangs falling on his face. "…and Roxas." He pointed beside Demyx at the shortest boy, who had ocean blue eyes and spiky golden blond hair.

Smiling, the headmaster sat up and motioned for them to follow him. Dumbledore left his office and leaded them once again through the school, while explaining about the four houses and the school subjects and at the same time showing them the classes, the Great Hall and the kitchen. He finally stopped in front of a full painting of a girl sitting on a cradle under a cherry tree.

"Hello Mina!" greeted the wizard the brunette girl.

"Good afternoon, Professor Dumbledore! How may I help you?" she asked innocently.

"I would want our new guest to stay here if you please!"

Mina smiled and let the portrait open, inviting Dumbledore and the four Nobodies in. the room was simple with blue and white walls and a fireplace on the other side. In front of it there was a low table and around it a sofa and two cushions.

An arcade separated the living room from the dining room, which was as big as the other chamber with a very long table and curtains on the walls. In front of then, near the fireplace was another arcade leading to a circular hall with four doors around it.

"This is where you will be staying. Now, you are free to go into the Forbidden Forest today, and tomorrow until the evening. I want you to be there so I can present you to the students and teachers. And no, I won't tell your names and you may not show your faces." He said quickly as they were about to protest. "Have fun!"

With that, he started walking toward the door when he was stopped by Demyx tapping his shoulder. "One more question Dumbledore, sir! Do you have a map of this place? I don't think Zexion will remember the way around and he's the brightest." He said rubbing the back of his neck.

"Yeah, you kinda lost me from the 8th turn!" added Axel.

"That's right! Well, you can ask Mina here for directions or just call Dobby!" in a puff of smoke, a short scrawny creature wearing all kind of sweaters, shorts and socks, with big green eyes and pointed ears, appeared holding a huge smile.

"How may Dobby serve you sir?" he asked bowing until his nose touched the ground.

"Dobby, I want you to help our guest in the future." Dobby looked at the four Nobodies and smiled brightly. "Yes sir! Of course sir!" he said bowing again.

"Just call his name whenever you want something! And the password is Peach Flowers!" were Dumbledore's last words before disappearing out of the room.

The portrait closed leaving the teens to look around them until a roar coming from Demyx's stomach broke the silence. Axel and Roxas broke into laughter and Zexion snickered while the Melodious Nocturne covered his abdomen embarrassed.

"Shall Dobby bring Master food?"

"Food will be nice!" yelled Axel sitting in a cushion.

"What kind of food Master?" asked the little house elf.

"Just anything." asked Demyx.

Dobby nodded and disappeared; only to come back a second later in the dining room. When the four Nobodies entered they saw the whole table covered in whatever dish someone could ever dream of.

"Wow!" they all said before starting to dig in the mountains of food.

"Thanks so much Dobby!" spoke Demyx swallowing. The small elf nodded hapilly and vanished again letting his masters eat.

…

Back at the Castle That Never Was…

"AXXEEEEELLLL!"

Luxord and Lexaeus looked up from their poker game to see a super angry Vexen storming in the room. Larxene, who was lounging on the sofa reading a magazine, looked at the door and burst into a fit of incontrollable laughter at the sight before her. Soon enough, Luxord did the same as Lexaeus tried to hide his chuckles without a good result.

Vexen glared at them with no effect whatsoever and growled. "Where is that damn freaking pyro?"

Larxene looked up to answer him but was overwhelmed by a new fit of laughter and couldn't help but bury her face in the white pillows on the sofa to stop. "He's…he's on a mission!"

Vexen growled and left the room holding the towel around his waist. On his way back he met with Saix who could have almost cracked if it wasn't for the Chilly Academic's murderous glare. "What happened to you?"

"Axel!" there is no need to describe how that word left his mouth.

"Well…he is on a mission! He'll be back in a few days!"

"And how am I supposed to get this off?" he spat pointing at the mess that once was his hair.

"Cut it?" Saix would have laugh at the dumb expression on the scientist's face, but added quickly. "But you should try hot water. Very hot water!"

Vexen mumbled a thank you and left in a hurry to his room, leaving Saix alone in the corridor. "I really have to tell this to Xemnas!"

Later…

"AGGHHHH! I'LL KILL YOU FOR THIS AXEL!"

…

In the Forbidden Forest…

"A…A…Achou!"

"Hey, are you ok Axel?" Roxas asked his best friend while slashing a Heartless with his Oblivion. Axel rubbed his nose and dodged a scythe by jumping beside his friend.

"I'm fine! I just hope I won't get a cold or something!"

Roxas nodded absently and leaped in the fight, in front of Demyx helping him with a few giant Heartless. Striking a few cords on his sitar, Demyx created five water clones, aiding the keyblade bearer defeat the creatures.

On the other side, Zexion slashed the Heartless with pages of his Lexicon while the flame-engulfed chakrams destroyed the flying ones above. "How many are they?" asked the red haired Nobody cutting his twentieth opponent.

"Xemnas said at our last meeting that it has been a massive increase of Heartless lately. It's not surprising there's a lot of them here!" replied Zexion avoiding a hit.

It was past midnight when Dobby woke them up and told them about the Heartless appearing around the lake. When they've arrived, they saw that the view wasn't as pretty as they thought.

"The good news…" began Demyx creating some water waves that washed up the black creatures. "The good news are that we're gonna have the rest of our lives after this!"

"The one thing I agree with!" added Roxas from behind him.

"As long as there won't be anyattacks…" spoke Axel sending a barrage of flames with his chakrams that burned the remaining Heartless as Zexion got rid of the rest.

Sighing in relief, Demyx whipped his forehead as his blue sitar vanished. "Great! Let's get back to sleep!" they all nodded, but when they entered the huge doors of the castle, the quartette found itself at the beginning of a long night that will be spend in a long maze.