AN: GUESS WHO'S BACK! Sorry about the wait guys. Just couldn't decide how to proceed here. The chapter should be a little longer than normal (not a lot because I aim for consistency).

-Good News-Bad News: (GOOD), this is where the canon divergence really starts taking off...like majorly (mainly because Lupin was a big part what happened here in canon). Also have plans to make this a series of fics (more world building and stuff, yay!). (BAD) Expect longer waits, I kinda have to a shit ton of research to make these worlds meld together since the timeline stops being useful here pretty much. You would not believe how expansive they are on their own.

-Just asking: Would you guys say yay or nay to a few epilogue chapters? It would be focused on How the characters spend their "before canon" summers...?

-Also: I don't know if it counts as a twist but did you guys see the second half coming? (Not entirely satisfied with it but I kept you waiting long enough)

Hogwarts Forrest, 10:13am

Kiritsugu started skipping more and more training sessions. More often than not now, it was either Maiya or Henry who were in charge of his extracurricular activities. Something was off and his new mentor didn't want him to know...which naturally made him curious as hell.

Nothing he could do about it now so he'd just have to wait.

Maiya was giving him more knife combat lessons. For a woman who could kick his ass with one hand tied, she was actually a pretty good instructor. Instead of Professor Emiya's spartan way of spar and correct, she'd adopt a more monkey see monkey do approach. He'd be shown basic moves and different forms, then be told to repeat that movement for a long period of time. He was currently on hour two.

She explained that it was to help with muscle memory, reducing reaction time and freeing brain space for tactics. Harry only understood because Henry was there to translate her explanation. Didn't save him from feeling like an idiot the first few times she did this exercise. No, relief only came when she first tested his progress.

It was a sparring match against her. Needless to say he was scared when it was announced, the woman could kill. He even closed his eyes when she began attacking. It was weird that he wasn't on his ass in the first few minutes, so he opened his eyes to check. Them she attacked again and he couldn't believe what he saw. He actually blocked her, he didn't know how but it happened. Like his body moved on it's own (of course she was massively holding back).

After that he never felt bad about looking silly again. Maybe there was some psychological training mixed in with stuff. He wasn't getting as irritated or angry with bullies anymore.

He broke out of his thoughts when he heard Maiya say break. It became the signal to stop the repetitions. Harry got excited because he knew what was next.

And there it was, the black key. Honestly, it was harder than he thought to get it working. Mainly it would just be him putting magic into it and trying to change it's shape. No luck on that front (slow and steady wins the race).

On the bright side he was learning patience with the lack of quick results. Plus, it gave him time to piece together the puzzle of Professor Emiya's change in habits.

'So... He's obviously doing something. Given the likely reason he was hired it has to be related to black. Maybe he's got a solid lead on him?'

'You're forgetting one thing. Maiya is still here. I'm sure it'd be nothing but time with Henry if he felt he was close.'

'Good point... Still, he's taking off a lot of time like he's got something. Just what is it?'

'We don't have enough information for that yet. Don't get ideas before you have data. Because you eventually-'

'Twist facts to suit theories instead of theories to suit fact. Yeah, I know we learned that last week.'

His internal dialogue was interrupted when he heard a sharp metal sound. Kinda lime a sword being drawn really fast.

His eyes didn't disappoint. The Black Key that wouldn't respond to him? It was now the size of a wand. The word happy would've been an understatement. He gave it a few test swings just because he could. It was much more manageable at this size than the fencing size. Speaking of which, he should take up fencing just in case. You never know when you'll need a magic holy sword.

After a while he tested to see if it was a fluke. The blade went back to it's full length.

Watch out wizarding world, Harry James Potter just got a very unique wand. If the vibe he was getting from it was right, thing was powerful too.

Eh, that last part made sense seeing as it was designed to deal with high level magic and spiritual threats (by priests no less). Oh man how he wanted to see if it could really cut iron.

His celebration was cut short when Maiya reminded him of her presence.

"Good, now we can progress on to the next step of training."

Oh, that was right... he was actually at the bottom of a mountain when it came to mastering the Black Key. Now came the hard parts. And given it was a pilfered item made by warrior priests, all the good techniques were probably horded. Not to mention had to be based in faith (which he learned was actually different type of magic energy than mana...who knew?). That, and he only had one so it's main use as a throwing weapon was limited.

Well, there went his good mood.

'Cheer up bud, it's still a really awesome magic sword/knife. Don't forget it's also your new wand now.'

'Oh, now you want to be nice to me?'

'Well, I'm stuck with you so I gotta make the best of it.'

Now that the subject was brought up, where did his old wand go? And just how long had it been missing?

Elsewhere on campus, same time.

Kiritsugu was kneeling down trying to get a good look at the tracks he'd been following. Animagi were tricky if you didn't know what transformation you were looking for. Changing form when out of sight was a very common tactic. This perceived advantage made them think they could elude anyone.

This was why Kiritsugu always forced them into areas with soft ground. It made the prints easier to spot and follow.

Thinking you always had upper hand got people killed. You never underestimate your opponent, especially not when they're an elite international assassin/mercenary who specializes in magical things. Although Kiritsugu did go to great lengths to separate his appearance from his reputation for that very reason. Being recognizable was handing the enemy a massive advantage.

Damn, the ground was no good. Either the target flew, or the prints were too small and got covered by the vegetation. He doubted it was the former.

Kiritsugu turned and looked to the wizard he drafted into the hunt (not that the man would've refused anyways).

Said wizard was looking down a different trail for whatever reason. The man did know the target personally so the mage killer didn't question it.

"Any luck?"

"No, it's a dead end here."

"Think you could get a scent?"

The wizard then took a wiff around. Ah! There it was. It was nice having a good sense of smell.

"That way."

"You take lead, I'll follow."

The man made tracking this enemy much easier. Months of search cut down to about two or three weeks. Would've been less if Kiritsugu didn't have classes to attend to.

After about 120 meters the man stopped, his ear twitching. Kiritsugu paused and did a perimeter scan.

Without warning the wizard flick his wand in a seemingly random direction. This caused their prey to change back and be lock in his human form.

The wizard had something of a grudge and immediately charged up the killing curse with his wand.

At the last minute Kiritsugu snatched his wrist and sent the aim of the spell off. It missed by inches.

The wizard broke the grip and glared at the mercenary, the silent question in the air. A question for which the mage had an answer.

"We need him alive to clear your name. He can't confess if he's dead, then you'd still be a wanted criminal. Do you get that? Black?"

Sirius Black, the man everyone was looking for. Kiritsugu Emiya actually tracked him down a few months ago and was prepared for elimination of target.

When he learned he'd been found, Sirius begged the other man to hear him out, claiming he was innocent. Luckily the mage decided to listen.

Given that his real mission was to see to the safety of Harry James Potter, he just couldn't take the chance the real danger was out there. Misdirection is a very effective tactic when done right after all.

After getting the truth (and confirming it through research), Kiritsugu helped hide . Helped him learn use his dog senses when human. He also fed the man because a starving prison escapee didn't make for an effective soldier.

Also gave him Harry's wand.

Working with a mercenary was quite the learning experience for Sirius. He almost couldn't believe it when he found out how many armed conflicts and assassinations the man had partaken in. It seemed Dumbledore might've over done it on this one (unless he knew something he wasn't telling). Well, all Sirius cared about was that Harry was in good, capable hands.

Now here they were, hunting down the real threat...one Mr. Peter Pettigrew.