Some mistakes are very small, but easy to fix. Putting your shirt on backwards is a mistake, but all you have to do to fix the problem, is pull your arms into your shirt, rotate it one hundred and eighty degrees, then stick your arms back out. The other end of the spectrum is quite a bit more...troublesome. Some mistakes seem small, but are actually quite large. Take Seina Yamada from Tenchi:GXP as an example of small mistake equals big problem. Seina recieved and signed a form ment for his friend, Tenchi. Poor Seina wound up as a cop with his own harem...in outer space.
This story starts in the reality Harry Potter calls home, with a wizard who is odder than most. Tom Davis was born to American parents residing in Alabama, who raised him in the United States for fifteen years before moving to Britain to work at the Ministry of Magic. At age eighteen, Mr. Davis joined the ministry as a "collector." A collector is someone who goes out into the world to inform children of their magical potential and brings them to the school where they will recieve their enchanted education. Most children live in homes that can be reached by using the floo network, but those few children who can't be reached by floo, must be reached by portkeys that are controlled by naming the location of the child. Once the collectors reach the end of the portkey travel, they use a "locator spell" to find the child they're looking for.
There's a bit of an issue with the portkey and floo methods, in that the operator must be very clear when speaking the location they wish to arrive at. This is because, while few people realize it, magic is semi-sentient and generally wants to help the witches and wizards who use it. When Mr. Davis was angrily ranting about his neighbors in his small wizarding community, he was also holding his portkey item. Let's take a moment to pause for a little information on multiple dimensions. In every reality, there is a mirror image of a person, even if they have a different name. Lord Voldemort in one reality is Orochimaru in another. Both are snake-like, bat-shit nuts, and are fixated on little boys. Floo travel works by magically connecting one fireplace to another, like a phone line you can travel or talk through. Portkeys are far more tricky, as they deal with the fabric of space and time. That means floo networks can't connect to a network from a different realm, but a portkey can cross the rift.
That brings us back to Mr. Davis, who was saying he should 'leave' his 'village'. His hillbilly expletive of "'fire' and 'tarnation'" was a small mistake... with very large consequences. You see, he had put emphasis on certain words when he spoke. The portkey didn't know what the hell a 'tarnation' was, but it did understand the word 'nation'. So the portkey misunderstood, "I should leave my village." *stubs toe* "Fire and tarnation!" What the portkey pieced together was, "Leaf Village, Fire Nation." There was a surge of magic, and poor Tom Davis was off to find an orphaned boy, whose parents had died in a natural disaster. This, ladies and gentlemen, marked the beginning of a cross-dimensional clusterfuck, the likes of which even Kami-sama herself couldn't fix.
This is a prologue as well as a challenge. For those who take this challenge, here are the guidelines.
Naruto is transported to Harry's reality with the forbidden scroll.
Harry teaches Naruto how to use magic, while Naruto teaches Harry how to be a ninja. That includes wall and water walking, ninjutsu, taijutsu, and maybe a genjutsu or two.
There isn't a list of what is on the forbidden scroll, so if you have any interesting techniques, go nuts.
Naruto beats the shit out of Malfoy for being an asshole, and winds up in a pairing with Luna.
Harry uses ninjutsu to fuck with Voldemort during their major fights. (Harry running along the ceiling as he throws spells is a cool thought)
Naruto still has the ability to use the fox cloak.
Harry winds up with Hermoine. (I think Ron is a bit of a jack ass toward Hermoine in the beginning, while Harry was nice to her.)
Naruto and Harry start hogwarts together, during first year.