This takes place in the fourth Harry Potter book, and somewhere before Tsunade-sama coming into the picture, but after Sasuke gets his Oorichimaru mark thing.

Disclaimer: Well, I don't think I own Harry Potter or Naruto. If I owned Harry Potter, I would be the third richest woman in Britain. If I owned Naruto I would be Japanese.

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Sasuke woke up with a start. He felt sick, and there was sweat clinging to his face, matting down his hair. The nightmare he had just woken up from was one of the most vivid and horrible that he had ever experienced. It almost ranked up with the ones he had about his parents, and his brother.

Sasuke sat up and put his hands to his head as he tried to remember exactly what the nightmare was about. There had been a man… no, a few men, and a snake. Sasuke shivered at the thought of Oorichimaru reaching him, even in his dreams. Unconsciously he put a hand to the cursed seal, which had begun to throb painfully.

Looking over at the clock, he saw that it was twenty past two. He pulled the covers up, but couldn't get back to sleep.

A few months later, Sasuke, after suddenly being assigned a mission, was walking through the forest of Konoha with the rest of Team Seven. He always hated these sudden missions. They would wait for hours for Kakashi to show up for training, only to realize that he could have spent his time preparing for a random, and usually boring, mission.

As it was, Sasuke had to deal with being with Team Seven for God knows how long, with only his weapons to accompany him. The day was almost over when they reached the outer limits of the forest. Deciding to camp there for the night, Sasuke pointedly chose a spot of ground to rest on that was far enough away from Sakura and Naruto to prevent them from annoying him too much.

As he slipped into sleep, he had a prickling sensation at the back of his mind, and when sleep fully claimed him he wandered into the land of dreams… and nightmares. There they were again, the man with the snake, and others, presumably his subordinates. Who was it? Sasuke strained to see. The man was unclear, but his thin, wraith-like hand came into focus. Was it Oorichimaru? He then noticed that the man had a wooden stick in his hand. Suddenly a flash of blindingly green light was emitted, and Sasuke again woke with a start.

His forehead felt like it was being split in half. Had he been captured by the enemy and injured? He couldn't think clearly for a few moments. Slowly the pain began to ebb away. Come to think of it, Kakashi hadn't told him the purpose of their mission yet, so he did not know exactly what to be wary of. After the pain subsided a bit more, Sasuke felt that he could move.

It was then he noticed that he was not on the ground anymore, but in a bed. Where were Sakura and Naruto? Had they been captured too? He looked around, but couldn't see anything. It was dark in his area of confinement. It seemed that the walls were made of cloth, and enclosed only the area of his bed.

Suddenly he felt a presence approaching. Sasuke readied himself for attack.

A dim ray of light hit Sasuke's face as the curtain from the side of his bed was pulled back. A worried looking face emerged. It was saying something, but Sasuke could not comprehend. He, for the face belonged to a boy, looked strange. He had flaming red hair and strange dots all over his face. Although many people in Konoha dyed their hair, Sasuke had never seen anyone with freckles before.

Slowly, the words that the strange boy was saying became clear.

"…are alright? You were tossing and groaning. Harry, are you OK?" The boy's eyebrows were pulled together in a worried frown.

"What?" Sasuke was confused, and slightly frightened, although he would never admit it to himself. He reached down for his weapons pack. It wasn't there. Of course, the enemy would disarm him. He chided himself for being stupid. "Who are you? Why am I here?" Sasuke needed to find out as soon as possible, and calculate the possibilities of getting back to his team.

In response the boy just looked at him oddly. "Harry, what do you mean? Are you sure you're alright?" The boy reached over to touch his shoulder. Sasuke grabbed his hand before it reached his shoulder, and twisted it so that the boy cried out and had to fall to his knees. As the boy fell he grabbed some of the drapery wrapped around Sasuke's bed. It revealed a circular room, with four other beds. A head poked out from one of the beds.

"Hey, what's goin' on?" A sleepy voice asked. Sasuke let go of the boy's wrist. The boy cradled it and held it to his chest. His eyes were wide with something akin to fear, before they narrowed, with dislike.

"What's your problem Harry?" Harry? Sasuke thought. Since when was he known as Harry? "God, you nearly broke my hand off! Next time I won't bother to check if you're alright." The boy stomped over to what was presumably his bed, and roughly pulled the curtains shut.

Nearly broke his hand off? Hardly. Sasuke took the opportunity to explore his surroundings. He got out of bed and looked around the room. The eyes from the boy from the other bed followed him, before he shrugged and went back to sleep. Sasuke noticed a door leading out of the room. He went through it, and followed the stairs leading down.

He found himself in a richly decorated room with the remnants of a fire smoldering in a fireplace. There were odd looking chairs, with big cushions, and portraits of people fitted on to almost every available inch of wall space. After a second he jerked in surprise when one of the people got up and walked out of their picture into the frame next to it.

Turning his head, he saw a mirror. Going to it he looked upon his reflection. He looked almost as he always did, but there was something different. His eyes were the same smoldering black that they usually were, and his hair was still as messy as it always was. However, he was now wearing round, slightly bent glasses. Even in Konoha people rarely wore them. He took them off, and immediately everything went blurry. He put them back on, and his reflection came back into focus.

Leaning forward he caught a glimpse of something beneath his fringe. He lifted up his hair to reveal a thin, jagged scar. Frowning, he traced a finger over it. It throbbed slightly, with a similar pain to when he felt his cursed seal was bothering him.

He looked around the room again. The windows were small, so even if he broke through them, he wouldn't be able to fit through. He could possibly need an escape route, depending on what happened when he finally met the enemy.

Those boys in the room didn't seem like the enemy. Admittedly they thought he was someone he was not, but when they figured out who he was, what would they do then? The boy who had come to see whether or not he was alright definitely wasn't a ninja, judging by the way he reacted to the simple grip Sasuke had on his hand.

As his eyes were scanning the room, they rested on a small wooden door. He was about to walk to it when it opened. A stern-looking, elderly woman came through. She seemed surprised to see him standing there. Sasuke immediately got into a fighting stance. The woman looked surprised, then quickly hid it in a frown.

"Harry Potter, what are you doing at this time of night?" She didn't wait for an answer. "Never mind. It's good that you're up. Dumbledore has requested your immediate presence in his office." She had a sharp sounding voice, and Sasuke felt a little intimidated by this woman.

"Dum-bleh-dorleh." Sasuke quietly muttered to himself. Was this the leader? He followed the woman out through the low door, and into a hallway. It was dark, but to his trained eyes he could see the vague images of more and more portraits lining the walls. It seemed to be the only sort of decoration, apart from the odd lamp, glowing dimly and eerily, brightening as they walked by.

After a series of twists and turns, and an interesting stair-case experience, the woman brought Sasuke to a large statue. She said something suspiciously like "cockroach cluster" and all of a sudden the statue started moving. It rose up in a spiral, and Sasuke stared at it, wondering how on earth it was moving.

"Well, go on then." The woman said, motioning to the moving stairs. Sasuke, very cautiously got on them. When the stairs came to a stop, Sasuke found himself in front of a large door. He stood in front of it, trying to prepare himself for whatever would be inside. He opened the door quickly and boldly. What was on the other side, he did not expect at all.

Instead of some sort of military personnel, was a wizened old man, with a long beard. He didn't march in as he had expected to. Instead he stood on the outer fringes of the room, gazing inside. It was like one of those dream-places. Hardly any wall could be seen. Instead cabinets and bookshelves filled all the space, and each surface was filled with an ancient book or strange looking object, magical and mysterious.

The old man himself was sitting at a cluttered desk, papers almost to the brink of cascading off. Next to the desk was the most beautiful bird Sasuke had ever seen. It was almost an ethereal as a summon-bird that Sasuke had seen another ninja call before. He could tell however, that this one was solid. He then noticed the man looking placidly at him. He sensed no animosity from the man, and relaxed ever so slightly.

"So, you've arrived." With a questioning frown Sasuke began to walk over to him.

Harry shifted uncomfortably in his sleep. It felt like something was poking him in the back. It was cold, so he reached for his covers… and groped around…. and reached further… but there were no blankets. Blinking his eyes groggily, he looked down to where his covers should be, but found that he was lying on the ground.

Fully awake in an instant he jumped up, reaching around for his glasses, before he remembered he had gone to sleep wearing them, too tired to take them off. Lifting up his hand to his face, he realized he wasn't wearing any. Blinking for a few seconds, he found he could see perfectly well.

Looking around, Harry saw that he was in a forest. The Forbidden Forest? No. This forest seemed more serene. The trees had lush green leaves, and there were plentiful signs of nice benign life-forms, a squirrel running up and down a tree here, a small bird chirping in it's nest over there. This was a relatively nice, sunny forest, rays of light glinting off the morning mist. He felt almost relaxed until he tripped over a tree root, incidentally the same one that had been poking him in the back.

It was then he noticed he didn't have his wand. Looking frantically around for it, awful thoughts of Voldermort and his plans started running through his head. Pushing those thoughts to the back of his mind, he scanned the forest floor. He had hardly been searching before he heard voices behind him.

Whirling around he saw two people, a boy and a girl, about his age. The girl had pink hair, and was currently in the act of grabbing the boy by the collar and shouting in his face. The boy, who was wearing mainly orange was also wearing a sheepish grin on his face, and holding his hands up in some sort of defense. It sounded like they were talking in a different language. The closer he listened however, the more the words came into focus. It was like having to squint your eyes to see something clearly.

"Naruto! I won't have you talking about Sasuke like that! How can you say something like that when you can't even match up to him! You should apologize!" The girl appeared to be doing a successful job of making the boy go deaf. The boy retaliated however, when the pink haired one said the last sentence.

"There is no way that I'm apologizing to an arrogant prick like that! After all, it's how he is!" Apparently the boy could yell just as loud as the girl.

Harry felt a little tentative about getting in between them. He did, however, need to find out where he was, and exactly why he was there. His skin prickled with the reoccurring thoughts of Voldermort, and what Voldermort's plans with him could possibly be. He prayed silently that he hadn't somehow fallen into a trap.

"Ummm…" Both the boy and the girl turned to look at him.

"Oh Sasuke," the girl began, "you're awake!"

"Yeah, Sasuke-teme, took you long enough! You're usually up before me!"

"Don't call him that!" They would have started arguing again, had not an older man with silver hair jumped down beside them, presumably from a tree. Harry visibly jumped in surprise, and the others looked incredulously at him, obviously shocked by his reaction. They shook it off and shouted at the man at the same time.

"YOU'RE LATE!"

"You said you would be gone for an hour and you've already been five!" The girl said accusingly.

"Well, you see, there was a creepy old woman who lived in a hut that I stumbled across when traveling through west of these woods, and…" Harry couldn't tell as the man's face was covered mostly by a mask, but he appeared to be smiling.

"LIAR!" Both voices rejoined. It appeared to be somewhat of a habitual custom. Harry was going to try to get another word in when suddenly the man turned to him.

"Sasuke, can I have a word with you?" He asked. "In private." He added, seeing the inquisitive looks on the faces of the two others.

"Umm, I'm sorry… sir… but I don't think," Harry began, before he was cut off by the man.

"Your questions will be answered in a minute." He then led Harry off by the shoulders.

When he was sure that they were in a secluded part of the wood, and after having to forcefully turn the blond boy away at least three times, the man finally stopped.

"A letter from the hokage." The man handed him a scroll. Harry took it hesitantly. He found some confusion in opening it, but when he finally did, he found it was written in a foreign character.

"I'm sorry, but, I don't know who Sas-uk-e is. I'm not him." Harry said. The panic he had first felt when he woke up and found himself in this forest was starting to wane, but a deep sinking feeling of worry was settling in his stomach.

"I know you aren't." Harry was almost certain that the man was hiding some sort of secret smirk beneath his mask. "I don't fully understand, but the details should be explained in the letter."

"I'm afraid I can't read it." Harry said, holding the letter out for the man to see.

"You can understand my speech can't you? It should work the same way for the writing." He motioned to the letter and Harry took another look at it. He stared at it. And stared at it. But nothing seemed to happen. He stopped concentrating on the symbols and was about to look up when all of a sudden they seemed to blend into letters. He scanned his eyes over the paper again, and the letters blended into words.

.Sasuke not are you that know to is one no ,Kakashi…What? Harry thought. Oh. I see, it's backwards. Harry pulled the scroll out a little further, then started reading from the end.

To Harry Potter, Concerning the Inter-Universal Exchange.

I know that this must seem a shock, but this is just one of those things deemed by the higher powers. Due to reasons unknown even to myself you are to spend a short time in this world, posing as the ninja Uchiha Sasuke. You must not let your teammates Naruto and Sakura know that you are not, in fact, Sasuke. You will remain in this world until the Powers-That-Be determine that it is time that for you to go back. The Uchiha is also posing as you, in your world. Good luck, and remember, with the exception of Kakashi, no one is to know that you are not Sasuke.

The letter was not signed. He stared in confusion at it, and then back at the man.

"This is… another world?" Harry asked. He was in shock.

"Hmmmm… the Hokage did not tell me all the details, but that's something like it, yes. Oh, and he also asked me to give you this." He started rummaging through his backpack, until he produced-

"My wand!" Harry leapt forward and grabbed it. How did that man have it? Regaining his composure, he looked at the letter. "So, are you Kakashi?" Harry asked. He was now finding it less difficult to pronounce the strange sounding names. The man, Kakashi, nodded his head in response. "Who is the Hokage?"

Kakashi answered, but this just lead to a long string of questions, about ninjas, missions, and weapons. Harry wasn't sure if he liked the sound of a world that was run by trained killers. There conversation ended abruptly however, when Kakashi suddenly seemed to disappear –or apparate- and returned shortly with a struggling Naruto.

"I just wanted to know if Sasuke was abducted by some weird guy pretending to be Kakashi-sensei! You were taking ages! What were you talking about, anyways?"

Kakashi dropped Naruto to the floor.

"We were talking about…" Kakashi appeared to look thoughtful, yet somehow managed to look suspiciously dishonest at the same time, "whether or not to use you as bait to lure the creepy woman out of her hut."

"GAH!" Naruto screamed in a most un-manly way, and quickly ran off to hide behind Sakura. Harry had his first experience of an anime sweatdrop, and wondered how anyone could believe such an obvious lie, coming from someone with such an obvious lying face.

He sighed. At least he had his wand. He would find a way out of here, somehow.

-End Chapter One-

I would like to take a short moment to explain my reasons for switching Harry Potter and Uchiha Sasuke. I'm sorry if someone has already come up with these ideas, however I have never read a Harry Potter/Naruto cross-over fanfic, and this is my first time writing one. These are my reasons why Harry Potter and Sasuke are interchangeable:

1) They both have black, unruly hair. (Okay, I know that's not really a reason, but whatever)

2) Their parents were both murdered brutally when they were young.

3) They are both surrounded by a very intelligent girl, and a fool best friend.

4) Marks have been left on them by two snake-controlling, immortality seeking, evil men. Voldermort and Oorichimaru are very similar, don't you think?

Please review! I'll accept anything!