Welcome to The Mortal Cross, a Harry Potter/Mortal Engines fusion fanfiction.

As with my other Harry Potter crossover, An Opus Alchymicum, it has been suggested that a synopsis of this story might be useful as a framework for the fic, as the other book series is not nearly as well known as HP, so I have decided to include one.

So a brief overview of Mortal Engines (not to be confused with Mortal Instruments, which is a different series entirely), the story I'm fusing with elements of the HP world. Set thousands of years in the future, in a dystopian and steampunk world created in the aftermath of a devastating atomic conflict, known as the Sixty Minute War, cities have become mobile and roam around the earth and eat each other for dwindling resources. Despite this, the civilisation is more akin to the Victorian era rather than the distant future.

This fic runs parallel to the events of the first Mortal Engines book, where secret agents of London uncover a powerful piece of old technology (Old-Tech) that they intend to use to dominate the world, and two young protagonists are thrown together to try and stop them. In my AU world, London's agents also unearth a link to even more ancient and archaic powers (ie, magic) and try to find a way to wield it as a weapon. This does not occur in the ME series, but I am using it as a plot device here. This takes the form of the discovery of the tomb of Harry Potter and his wife, Hermione, from an AU past where the HP world was a matter of historical fact. Harry and Hermione are essentially reborn into the ME universe, initially with no memory of who they once were. They then slowly start to learn the mysteries of their past and set off to solve them. It should be noted that Harry and Hermione will be necessarily different to their original characters, and the story will not involve time-travel, dimension hopping, or a re-hashing of HP canon events. I simply use the HP world here as a plot and narrative tool, but this story is set very much in the Mortal Engines universe.

And that's it. There's no complicated high fantasy elements to explain, no difficult timelines to fuse. If you can imagine towering cities rolling around on caterpillar tracks gobbling each other up, and can stretch to the idea of Harry and Hermione being forcefully reincarnated into new bodies in this world, then you're good to go.

Hope you give it a try.

Thanks

Chapter One: Gut Duty

It was a clear, cloudless night and the city of London was trundling along at an idling speed of about fifteen miles per hour. It had just eaten a meagre, one-tiered fishing town that it had happened upon in the dark, and was now focusing its energy reserves on dismantling the pitiful little thing. As such, the engines were ticking over only lowly ... the steady throb of the motors reduced to a gentle hum, as the great Traction city devoured its feeble excuse for prey.

The unexpected quiet made it simply perfect for an evening stroll through the flower gardens of Kensington Park. There were only a few people about, mostly the gardeners, tending to the plants and shrubberies that lined the walkways of the open-air park at the heart of Tier Four. There was a recently graduated Apprentice from the Guild of Engineers sitting alone on a bench nearby, his bald head gleaming in the stream of moonlight just peeking around the sharp rim of Tier Three just above him. It looked as if he had just received his Guild Tattoo, a Red Wheel on his forehead just between his eyes, as the skin around the tattoo was as sore and scarlet as the wheel itself.

Hermione Granger tucked her arm tighter into the crook of her boyfriend's arm and tugged him closer. This was how she liked things best, when it was just the two of them. Walking in the park together was one of Hermione's very favourite things, and she never wanted it to change. But she knew that, very soon, everything was going to change.

"Are you excited to get your tattoo next week?" Hermione asked as they walked past the Engineer.

Harry Potter, her boyfriend of five years, quirked a look down at her. "Are you excited to get yours?"

"Well, it will be nice to finally graduate," Hermione replied sniffily. "But I just wish the tattoos weren't so big. Having a great old blue eye plastered to my forehead will take a bit of getting used to!"

Harry laughed heartily at that. Hermione liked it when he laughed. After such a wretched childhood, she didn't think he could ever have too much joy in his life now. But as she intended to be part of his life forever, and the source of his most profound joy, she was comforted to know that his happiness was a power stowed safely in her own hands.

"See it as a mark of distinction," Harry went on. "You will be an Historian, First Class. It's something to be proud of. I'm proud of you."

Hermione smiled shyly to herself and pulled Harry closer still. "Will it hurt, do you think? The tattoo?"

"Maybe a little," Harry replied. "But I'll be right there by your side, so you can hold my hand until it's all over."

"And for the rest of our lives after that," Hermione swooned. She turned and gave Harry a chaste peck to the cheek. He was too tall now to reach his lips without tugging his head down, and who could say how amorous they would get if Hermione initiated a kiss like that, especially as there was no-one around to stop them from getting carried away.

So they walked on through Kensington, out onto The Strand, and made their way to the elevator station at Bank, stopping at the viewing platforms that looked out from the edge of Tier Four, quietly watching the ruined earth drift by as the Great Traction city of London trundled along. Hermione turned her head to look up at the sky above Tier One, with the great dome of St Paul's swaying gently as the engines thrummed rhythmically from down below.

"How many stars do you think are up there, Harry?" Hermione asked.

"Billions beyond count," Harry mused. "But I'm more interested in the steel moons that the Ancients sent into orbit. Some of those twinkles are from them you know, not stars."

"I know. I told you that, Harry!"

"Did you?" Harry quirked. "Ah well, it was a fascinating bit of trivia however I learned it. I wonder what they were used for, those metal satellites?"

"We can only guess," Hermione sniffed. "The Sixty Minute War wiped out our only ways to communicate with them, didn't it? And after hundreds - or even thousands - of years of silence, they might not even work at all anymore. It's quite sad really, don't you think? That they are drifting round and around in their quiet laps of the planet, wondering why their creators suddenly stopped talking to them. Seems such a terrific waste of human knowledge and ingenuity."

"I'll be sure to put that observation into my exam paper next week!" Harry teased. "I'll call it 'How the Ancients of the 21st Century Ruined It For Everyone Else With Their Foolish Wars!"

Hermione rolled her eyes at her boyfriend and guided him towards the elevator station. They were on Gut Duty tonight, every Apprentice Historian's most despised task. It didn't matter whether you were First Class (like Harry and Hermione), or a mere Third Class, such as the Apprentice they had been assigned to carry out the more dirty work for them this evening. Nobody liked going to the hot and acrid bowels of London unless they really had to.

Harry was glad to see the boy. They were kindred souls in a way, having both lost their parents when they were younger and both having been taken in by the Guild. Harry had always felt a bit like a protective older brother to him.

"Hullo, Apprentice Natsworthy!" Harry announced jovially, as he and Hermione crossed the Gut to meet the boy. "Who did you annoy to get saddled with this joyous task this evening!?"

Tom Natsworthy turned, grinning at the sound of Harry Potter's voice. If he was going to be working with Harry tonight, it might not be so bad after all. He perked up at once. He'd rather Hermione Granger not be there this evening ... but then again, wherever Harry went, Hermione was sure to be nearby somewhere. That's just how this pair of young lovers were, and everyone knew that. It wasn't that Tom disliked Hermione ... in fact, it was rather the opposite, as he liked Hermione a lot ... but she was always very kind to him, even though she didn't need to be. Tom simply didn't know how to behave around a person like that, wasn't used to it at all. It didn't help that she was unconventionally pretty, either. Tom always became a little tongue-tied around her because of her understated beauty.

"Evening Harry, Miss Hermione," Tom muttered, colouring as Hermione smiled at him. He really needed to get over this. "I was cleaning the exhibits, in the 20th Century Gallery up at the museum, when London hit a giant sink hole. I fell into a statue of Pluto ... you know, one of the animal-headed Gods of lost America ... what am I saying? Of course you know that, sorry ... and then he fell into the statue of Mickey, breaking his ear off. Chudleigh Pomeroy was very angry with me, as you can imagine, and so I got stuck on Gut Duty for the rest of the week."

"Hard lines," Harry chuckled. "But perhaps it wont be so awful. There are fierce rumours that Mayor Chrome is going to take London back across the land bridge into the Great Hunting Ground soon."

"And if London eats a few towns and small cities along the way, it'll be ever so interesting down here then," Hermione took over eagerly. "Think of all the amazing things you might be able to find amongst the catches, to add to the Museum or the University."

Tom perked up at the thought of that. He suddenly felt a desperate urge to find something important tonight, something impressive to give to Miss Hermione. One of those nice, shiny discs ... that the Ancients called a 'seedy' ... or something would do, not that they had any way of reading the contents of those items anymore. But it might be enough to earn Tom one of those nice smiles again.

"So why are you down here?" Tom asked, as Harry began to lead them away towards the massive sorting bins. "First Class Apprentices never have to do Gut work unless they do something terrible, and even then they only get the light work."

"Hermione and I volunteered," Harry explained. "We often come down here to sift through the collection skips, looking for anything interesting or functional that isn't of use to anyone else. Last week we came across some sturdy sun shutters that will be just perfect for the front window of our airship. It saves us some coin if we can recycle anything like that."

"When will your airship be finished?" Tom asked, remembering that Harry had told him how it was being built brand new for them over at the dockyards in Greenwich. He was a little envious of that. Tom and Harry were alike in many ways, but Tom's parents hadn't left him a small fortune - in the way that Harry's had - when they had died in the same accident. Not that Tom begrudged Harry for it. Harry was a kind and friendly soul deserving of such things, as far as Tom was concerned. But Tom had always thought that having his own airship would really be something.

"By the time we graduate to full Guild members, the airship will be ready," Hermione replied for Harry. Tom noticed she did that a lot, as if she and Harry shared a single mind or were on some secret wavelength that only they could sense. It was almost as if they could read each other's thoughts. Tom envied Harry a bit for that, too. In all his daydreams about saving beautiful girls from air-pirates or the Anti-Traction League, Tom soon developed similar telepathy with his fantasy damsel in distress, but he'd have given anything to have that with a real-life someone. Talking out loud to the skeleton of the giant Blue Whale up at the Museum wasn't quite the same.

"And do you have a name for the airship yet?" Tom asked.

"We've christened her The Jily Harmony," Harry told him. "We'll have a proper naming ceremony when she's ready, maybe throw a party. You'll have to come along when we do."

"Thank you," Tom muttered, slightly embarrassed at being so singled out by a First Class Apprentice. 'Thirds', like Tom, were never usually treated so well. "And what do you plan to do once you leave London, if you don't mind my asking?"

"We're going to become aviators for a bit," Harry explained. "We'll fly over to Airhaven and become sky traders, shuttling passengers and cargo to all the great cities. We want to see Arkangel and Bayreuth and Milan. That's a way to do it and earn some coin."

"And when we have saved up enough, Harry and I are going to get married," Hermione took over, looking up fondly at Harry. "Our plan is to spend the winters in the sky, then over the summer we'll go on great expeditions to the wastes of America, see what Old-Tech we can dig up in the ruins of Africa, and even travel to the static settlements of the Nuevo-Maya. It promises to be a life full of fun and adventure."

"It sounds incredible," Tom agreed, wistfully. "I hope you'll come back and tell me stories all about it. I often wonder what it would be like to travel the Bird Roads and see all those famous cities ... but I doubt I'll ever get to have an adventure like that of my own. I'll be cleaning Chudleigh Pomeroy's hob-nailed boots from now till the day I die I expect!"

Harry chuckled, Hermione looked over in sympathy and Tom turned his eyes down meekly. He'd said too much ... it was best to focus his attention now on finding something useful in the row of giant skips, which housed the spoils of London's part in Municipal Darwinism. Cities ate towns, towns ate smaller towns, and the smaller towns gnawed at the grubby static settlements and the resource-rich hills that dotted this wet, mountainous region of the North, that the Historians said was once the island of Britain.

So any cache that London absorbed by ensnaring prey was brought here to the Gut. Anything useful was recycled as engine parts, or burned in the giant incinerators that helped generate power for the city. Then the Historians took anything of importance to them, the Guild of Merchants took any money or precious metals recovered and so on, until the entire catch was re-purposed for London's needs.

But Tom knew that he had little chance of finding anything with which he might impress Miss Hermione tonight. It had been ages since London had hunted any reasonable prey, so anything of real value would have been stripped long ago. But he dived in with relentless hope, fishing around among the discarded clothes and broken furniture that had yet to be added to the furnaces.

And then, just under a cracked mirror with an unreadable inscription, Tom's fingers touched the edges of an object that sent his heart beating wildly. He had found something, something hidden in the depths of this debris! He recognised the feel of it, the texture. It might be something ancient and important, it might be a compendium of stories from one of those wacky religions of the Pyramid Era, but whatever it was, Miss Hermione was bound to be interested in it.

After all, everyone in the Historians Guild knew just how much Hermione Granger loved books.

"Ooh, is this for me? Thank you so much, Tom," Hermione beamed, causing Tom to flush deeply. Hermione turned the book over in her hands. "Look at this, Harry! Look what Tom found. The binding is beautiful and these pages ... they're not paper ... this is parchment, Harry! This book must be very old."

"It is?" Tom asked, looking over in surprise. "How can you tell?"

"All our books are made out of many-times recycled paper now," Hermione explained. "That's why the pages tend to look beige, as we don't have the treatment solutions to make things brilliantly white anymore. But these pages aren't like that. They are also thicker and heavier, which makes me think that they are parchment, not paper."

"The curious thing about parchment, of course, is that it hasn't been used for centuries," Harry whispered, looking at the book over Hermione's shoulder. "We have forgotten the technique for creating parchment pages, and most books from the age that used them are long lost. This might be a very critical discovery, Tom. Well done."

Tom Natsworthy puffed out his chest, swelled by his own importance. "What could it be, do you think? Does the book have a title?"

"Yes, yes it does," Hermione replied, sweeping a layer of dust from the deep purple cover and lifting the book towards a nearby lamp. "It's called 'Hogwarts: A History'."

"Hogwarts? What's that? Or where is that?" Harry frowned. "Is that an old country? A forgotten city? It doesn't sound familiar."

"No, not to me either," Hermione replied, the light of adventure sparkling in her eyes. She held up the book again and began thumbing through it's pages. "But one thing is for sure, Harry, it's going to be so much fun finding out!"

Harry grinned, then looked over at Tom, still full up with his own sense of self-satisfaction. Harry grinned at that, too.

"Well done, Tom!" Harry laughed. "I know you were looking for something impressive to find for us, but you've done so much more than that ... you've given my Hermione a project! Something for her to research and delve into! And if there's one thing my girl loves more than books, it's homework!"

"Shut up, Harry!" Hermione chided gently.

Then she took his hand and excitedly guided him away from the Gut, her new book stowed safely under her other arm. Their first great adventure was about to begin.