The smallest of events can change the course of history. In another time, Voldemort's terror troops roamed London attacking the nonmagical without anyone to stop them.

However, in this instance, one of the younger recruits tripped, leaving the boundaries of the wards that would alert them to the Aurors showing up.

Right into full view of the Magus Association's Enforcers. They stormed the wards, killing every Death Eater there and erasing all evidence of magic from the normal folks.

Which lead to this...

Kiritsugu Emiya was the infamous Magus Killer. And he had been hired to deal with the top Death Eaters.

So he went from house to house, killing all those marked inside. He was doing more to end Voldemort's reign of terror than Dumbledore had done with his precious Order of the Phoenix.

"We must stop whomever's doing this!" said Dumbledore.

"For the past month, there have been over fifty murders...all of them marked," said Moody, explaining to the others.

"I say we give the one killing them a medal and a shot of fire whiskey!" said Sirius Black.

Dumbledore shot him a dirty look. He shot James one when he high-fived Sirius.

"This person is a murderer!"

"He's a hero! Tell them the rest Moody!" said Lily angrily.

"Whoever is killing the Death Eaters, they are only killing those with the mark. Children and those who are just in the wrong place at the wrong time are left alone, aside from being a little groggy if they happen to stumble across this person. Clearly they were just after those who work for Voldemort or his people," said Moody.

"Like I said, this man is a hero," said Sirius flatly.

Dumbledore could see he would get nowhere with Sirius backing this mystery killer up. So he decided to give Sirius a reminder of who he served and sent him and James on the next target of this killer...based on his pattern anyway.

Sirius and James went in, to get some information on the Death Eaters inside. They found a massacre. Apparently it had been the home of a small vampire clan as well as Death Eaters.

The only living thing in the house was a man with a bloody knife and smoking set of guns. His eyes were dead inside.

Sirius immediately asked "Are you a Death Eater?"

"No. I was hired to take them out," said the man flatly.

"You the same bloke who's been going around killing them in their sleep?" asked James.

"I am," he replied, tensing for a fight.

"Well, there's only one thing to do then," said James solemnly.

"It seems we owe you a drink," said Sirius with a wide grin.

"What?" said the man completely baffled.

It was a somewhat cleaner Kiritsugu who walked into the Three Broomsticks, having been allowed inside James' house to at least clean up. Apparently Sirius fully planned to buy him a drink for taking out some of his less than savory family members.

"So, why exactly do you owe me a drink?" he asked finally.

"Because you're a hero! Aurors take too long and they never bother to do anything besides arrest people. Dumbledore won't let us take out their bases, despite knowing where they are," said Sirius.

Kiritsugu's blank stare now had a rather startled look.

"You actually consider a killer like me a hero?" he said in shock.

"Hell yes I do! You may be killing people, but you've never gone after anyone who hasn't been marked as far as we're aware! That makes you a hero in my book!"

"Yeah, Dumbledore won't even let us use any lethal curses! He thinks he can 'reform' a bunch of killers and rapists," spat James.

"Dumbledore is the leader of the other side? The one with those ridiculous phoenix patches on their clothes?" he asked.

"That would be his side," said James in disgust. Really, it was bad enough seeing them the first time, but using them as identification? Really not smart.

"We burned ours. Everyone already knows we side with him anyway so there wasn't any reason to wear them," said Sirius.

"So who hired you to deal with the Death Eaters?" asked James.

"The Magus Association finally noticed your little war and hired me to deal with it," said Kiritsugu flatly.

"Magus Association?" asked Sirius.

"Clock Tower ring any bells?"

"Never heard of it," they said in unison.

Kiritsugu pinched the bridge of his nose. Just how far back were these people?

"Let me put it this way, how far back is your technology. What was the last invention put into public use?"

James looked at Sirius and they replied in unison "Indoor plumbing."

"Please tell me you're joking," he said.

"Actually I think the last fad from the non-magical side was the Knight Bus, which has been in circulation for the past fifty years. After that it was indoor plumbing," said James.

Kiritsugu looked like he wanted to bang his head on something. On the plus side, it made his job so much easier if they were so behind. On the negative, they needed a reality check, badly.

Kiritsugu found himself with a home base of sorts in James's house. Lily didn't seem to mind having a killer in the home, considering how well he got along with their son Daniel. Daniel had his mother's red hair and his father's brown eyes. Daniel seemed fascinated by Kiritsugu's knives, though he never touched them.

When they went into hiding because of a prophecy, Kiritsugu was one of the few they entrusted their location to.

Sirius was of the opinion they should have made Kiritsugu their secret keeper, but he was outvoted thanks to Dumbledore.

Six years after meeting Sirius and James for the first time, Kiritsugu was selected as a master for the fourth Grail War in Fuyuki. By that time, James and Lily had been killed by Voldemort himself and their sons were missing. According to rumor, Harry was at his aunt's and Daniel had been taken. No one knew where he was at all, which bothered Kiritsugu.

He had been rather fond of the boy, and of the family. It was rare to find people who didn't hate him for his profession and actually considered him a hero, of all things.

Shortly after the war was ended by Kiritsugu, he found a single child amongst the flames, half dead.

It wasn't until after the boy had been cleaned up that he recognized him. Daniel Potter had been in Fuyuki the entire time.

Shiro started cooking breakfast. Ever since he was a kid, he had been designated the official cook of the house. Kiritsugu had no sense of taste to speak of when he was alive. Today he turned eleven, and he had the weirdest feeling something big was supposed to happen today. When nothing did, he felt disappointed for a reason he couldn't explain.

It wasn't until nearly a year later, in July, that something finally did happen.

A horned owl flew into his house with a single letter in it's beak.

Shiro took it from the owl, and his jaw dropped when he read what was in the letter.

"Dear Mr. Emiya,

In response to a request by your former parents, we have waited for you and your brother to reach the appropriate schooling age before sending your letter.

We are pleased to inform you that you have been accepted in Hogwarts School of Witchcraft and Wizardry. Due to the fact that all magical travel has been banned to prevent issues with the last war, a teacher will arrive at your residence no later than ten o'clock next Sunday to escort you for your supplies. You may ask questions then.

Sincerely Minerva McGonagall."

Shiro reread the letter several times, but it kept saying the same thing.

Kiritsugu had mentioned he had known Shiro's birth parents, and that they had died due to a mass-murderer finding them. What few stories he had tended to make Shiro laugh.

He didn't know he had a brother though.

Shiro stared at the greasy haired man, who was looking at the house with interest.

Apparently he had been chosen out of the staff because he was the only one who had been Japan long enough to bother learning the language.

Shiro let the man in, and he took his slip on shoes off without being reminded.

Once Shiro handed Snape-sensei his tea, the man got down to business.

Snape answered all his questions about Hogwarts, even some Shiro hadn't thought to ask. Since they would have to take an international flight, Snape took one of the spare bedrooms for the night since Shiro had to alert his 'guardian' Fujimura Taiga about the fact he had accepted to go to a school in England for seven years.

Shiro was more interested in the goblin's weapons than he was about his gold, something the goblins took note of immediately.

"We're here for Daniel Potter's school funds," said Snape shortly.

A younger boy, one with messy black hair perked up when he heard the last name.

"Did you say Potter?" he said hopefully.

Snape twitched, before he looked at the boy escorted by Hagrid.

The child looked like some orphaned waif, wearing too big clothes and broken glass frames. Snape saw old bruises and a too skinny frame under the oversized clothes.

The second he saw the scar, he realized this was the famous Harry Potter, youngest son of his hated nemesis James. His eyes were pure Lily.

Hagrid looked unsure as to what he should do at this point, so Snape decided for him. He knew Dumbledore planned to have the man pick something up for him, so why not curb some of the boy's Gryffindor tendencies early on?

Hagrid reluctantly agreed to leave both boys with Snape, as he was already escorting the older Potter child anyway.

Shiro looked at the boy that Snape said was his younger brother. Apparently they had gotten opposing traits of their parents. Shiro had Lily's red hair and James' brown eyes, Harry had James' messy black locks and Lily's green eyes.

Shiro also noticed how the boy flinched at loud noises and if someone so much as brushed up against him.

Griphook opened the vault and both boys gaped in shock. There was enough gold in there to pay for Shiro's house five times over!

The two grabbed double handfuls of gold (one bag for each of them) and Snape lead them up to the Alley for shopping.

Harry tried to talk to the older Potter, but because of the language barrier was unable to. Shiro could only manage broken sentences in English, having just started those this year. Finally Snape hit both with a language charm, and the two hit it off over cooking of all things.

Because the blood wards Dumbledore had promoted so much required one of Lily's blood relatives to even work (though why he couldn't just keep the boys together he had no idea) Snape decided to kill two birds with one curse.

It took little convincing for Harry to gain a temporary Japanese citizenship and for the Fujimura family to become his legal guardians (something Petunia was far too happy to hand over). Since he would likely learn Japanese from Shiro (who no longer answered to Daniel, having been legally and magically adopted by Kiritsugu shortly after the fourth grail war) he made sure to get a translation charm for Shiro so he could teach Harry the language without mangling the English language.

Taiga took one look at the scrawny form of Shiro's younger brother and glomped him.

"SOOOO CUTE! He's as adorable as you were at that age Shiro-kun!"

"He knows how to cook," said Shiro quickly.

"Oh really?" said Taiga with no little amount of drool.

Harry shot Shiro a look that clearly said 'Traitor!'

Once she got a taste of Harry's cooking skills, she was determined to never let the kid go. He was as good as Shiro was!

"Is she always like that?" asked a terrified Harry later when she left.

"Unfortunately. Once she tastes how good your cooking is, she never lets you go. On the plus side, she can beat the hell out of any wizard who's stupid enough to try and separate us and her grandfather will keep the authorities from trying to force you back to that awful neighborhood," said Shiro with confidence.

To be fair, one of the things the Head of the Fujimura group had asked of Kiritsugu was something to keep most magical influences from affected his decisions.

It had kept ten wizards since then from trying anything that would harm Shiro in the long run, and he had considered it one of the best investments he had ever made.

Kiritsugu had once commented that because of the cursed shinai's influence, Taiga Fujimura would never be swayed by magical means. Putting her to sleep, or a simple misdirection, was still entirely possible however.

Because of his mistreatment of their aunt, Harry often shared the room with Shiro at night, something that Shiro never commented on. Harry never thought Shiro's dream to be a super hero was silly, or childish, but rather cool.

And for the first time in ten years, the brothers were able to sleep easily, knowing that their family was complete again.

"Where is it?" asked Harry nervously.

"Relax Otouto, Snape-sensei said that we had to walk through the third pillar from the ninth platform to get to ours. Something about there being a small pocket dimension separating the two areas," said Shiro calmly. No matter how often he said it, he loved being able to call someone little brother.

It was nice to have a family again...especially one who believed your dreams could be true, no matter how odd they were.

It took the combined efforts of Shiro and Harry to get the trunks onto the racks above, and once they did, they went over the basics of Magecraft, as explained by Kiritsugu to an interested Shiro, and passed onto Harry by his brother.

It was during these little sessions that Shiro belatedly realized that he had been creating his circuits incorrectly for years when Harry pointed out that he had been accessing them the wrong way.

As a result, Shiro had made more progress in a week than he had in five years.

He had even figured out his element, which was Sword. Odd, but workable. Harry's was Wind and surprisingly Water.

About ten minutes after sitting down, a younger red head (which looked more like ginger than an auburn color than Shiro's) asked if he could sit down, but after seeing how uncomfortable his little brother was when the kid saw the infamous scar (which he swore to get looked at over Christmas break) he kicked the boy out.

He also threw out a bleach blond daddy's boy and his twin goons (or at least he assumed they were fraternal twins...they were so alike it was disturbing to consider the other possibility) and a bossy brunette who went on and on about the books she had read about his brother which were obviously a load of tripe.

The only ones he didn't throw out were a pair of identical twins named Fred and George, and that was because they showed something the first five idiots hadn't. Common bloody sense. That and they were older brothers (to the ginger, but they didn't learn that until much later after a prank on the kid who they found out was named Ron) so they were able to tone down their excitement at having met the famous Potter brothers to a bare minimum.

Shiro had a mean left hook, likely inherited from their mother Lily.