Disclaimer: I don't own Harry Potter and Naruto.

Chapter one: The train

Platform nine and three-quarters tends to be terribly busy on September the first. Smoke curls through the air. The weather is surprisingly nice today, but there's no bird to hear over the tears of children and parents separating and the wailing of younger siblings wanting to go too.

Shisui sighs, closes his eyes and presses forehead against the cool glass. He can feel his breath fog on the window. This is the fourth time he's gotten onto this train in order to get to Hogwarts, and he wonders if he will ever get used to it. He likes sitting alone during the journey- the flurry of his friends and their troubles can come later. He enjoys the peace of an empty compartment and the rocking movement the wheels on the rails create.

At the sound of his compartment door sliding open, Shisui cracks an eye open, peering in the direction it came from. There's a boy in the door opening. He's small and scrawny, all pale skin, clothes too big for his frame and messy black hair. He startles a little when he sees Shisui, but shuffles inside quickly, to let two rather lanky red-haired boys through.

Shisui catches a glimpse of green eyes, and his heart stands still.

Was that-

The boys seem to be talking about something, but Shisui can't hear it over his suddenly extremely loud heartbeat, that fills his ears and shakes his body. His breath catches in his throat.

Is it- No. It can't be.

Shisui quickly grabs his bag and picks up his notebook. He forgets that the dip pen is attached to its side, though, and hisses when the sharp point cuts his finger. Damn it - the small cuts are always the meanest.

Cursing quietly, he fishes an Elastoplast out of his bag, but it's hard to get the backing off with one hand.

''Do… Do you need any help?''

Shisui jumps slightly and stares.

The boy is in front of him, biting his lip, brow furrowed. Hesitantly, he reaches for the Elastoplast and when Shisui makes no move to stop him, he takes it. The boy takes off the backing and looks at Shisui, shifting uncomfortably, before realising that Shisui, for all his ninja skills, most likely can't put the bandage on without smearing it with blood.

Shisui holds out his finger. Quietly, the boy sticks the plaster on, bright green eyes focused on the wound.

The boy's hand lingers on his, and Shisui can't help but remember pale fingers gently wrapping bandages around injuries much more serious than this. The gaze that accompanied it had always been a thing Shisui could physically feel, and he wonders if he's imagining it- have his senses finally decided to deceive him, instead of others?

He clasps the boy's hand, the bony thing almost disappears in-between his far larger ones. Green eyes widen behind glasses held together by tape, and Shisui smiles gently. There's so much innocence there, even if the boy tenses slightly at the touch. A glimpse of intelligence that the kid is unable to bury beneath uncertainty and a skittishness that make Shisui's chest feel too tight.

''Thank you,'' he spoke.

He can see the hesitation in the way the boy moves, but the child shakily puts a hand on top of his, and gives him a smile. It's shy and small, and there's a bit of hope in there.

''No problem,'' the boy mumbles. ''I just wanted to make sure you were alright.''

''I'm okay now,'' Shisui says with a lump in his throat, but for the first time in forever, he means it.

He's okay. Because he is sure now. He knows those eyes, he knows this boy.

New world or not, he would recognise Itachi anywhere. And this time? This time, he sure as hell isn't letting go.

''I'm Shisui!''

When Harry's name is called out during the sorting ceremony, Shisui almost chokes on his own spit when he hears ''Potter''. He grabs his glass and begins gulping down pumpkin juice in order to stop coughing, and stares at the child on the little stool in front of the hall.

The boy who lived.

Shisui can feel a headache coming up. Damn it, Itachi!

But Harry grips the stool so tightly that his knuckles turn white, and the hat is so big that it covers his eyes and ears. His face is white as a sheet, and Shisui can feel his nerves like they are his own.

He knows that this Itachi truly is a child. A scared little boy in a world he doesn't know at all. And he remembers how his cousin used to be. Less open, but this Itachi has never had any kind of shinobi training and has no need to put up a façade. He's young and untainted by the horrors of war.

The hat shouts ''GRYFFINDOR!'', and the entire hall is cheering. Shisui can hear someone yelling: ''We got Potter, we got Potter!'' somewhere further down the table, but he doesn't care. His eyes are on one person only. Harry scrambles of the stool and hurries towards the Gryffindors- his gaze gliding over the people, searching for a familiar face. When Harry notices him, Shisui pats the empty space beside him.

And as Harry climbs into the seat, a breath-taking smile on his face, Shisui makes another vow. This time, he'll live.

For Itachi.

''Change is the constant, the signal for rebirth, the egg of the phoenix.''

Christina Baldwin

Authors note

First off, I'd like to thank Shadowblayze for allowing me to use their plotbunny! This was the exact idea she posted on Tumblr:

"Uchiha Shisui had grown accustomed to his new world's strange ideals, so it really doesn't surprise him when he finds out about Hogwarts.

Shinobi were myths to most of the civilians back home, too.

However, just because he'd voluntarily sacrificed himself in order to try to prevent a civil war the first time around doesn't mean he's all that excited to do so again. Especially for a group of people he feels no sense of responsibility towards- and, quite frankly, he doesn't like much.

Seriously. The propaganda agenda behind the idea of the 'Boy-Who-Lived' nearly makes him want to hurl.

But just when he thinks he's got a plan lined out- after he's settled into his comfy train compartment aboard the Hogwarts Express- the door opens.

New world or not, he'd recognize Itachi anywhere.

Dammit.''

Check her out on Tumblr and ff net! She writes great fics!

Also thanks to I.W.P.- chan (also on Tumblr and ff net, and she has these AMAZING KHR fics!) who got me totally hooked on her Tumblr even though I don't even have an account (she made me YOI trash, people. Love her). I got onto Shadowblayze's Tumblr page via a reblog from her.

I had a lot of fun writing this! I'm marking it complete for now, but I still have a few ideas for some scenes, so I might add another chapter at a later date! Also, Shisui uses a dip pen instead of a quill, because I do not believe that after a life time of either using hand signs or weapons made of metal, Shisui would feel secure with only a wand on him- even if a dip pen on its own isn't exactly lethal either.

I hope you enjoyed it, and constructive criticism is always welcome!