Disclaimer: Harry Potter is the property of JK Rowling, as such all rights, royalties, characters, and settings belong to her.

Author's Note: Unlike Son of Prongs, which is designed to largely follow the canon stories quite closely, One World will play much looser with the original story. Having Hermione and Harry act as siblings fundamentally changes how Harry interacts with others, especially Ron. This causes something of a chain reaction in the story.

Originally, I was going to have this as separate novel-length stories, but I quickly realized as I started plotting out the years in my head, that it would work better as a multi-part single continuous story since the climaxes shift around a bit. Each part is roughly a year in the life of our characters. Ironically, there are eight parts, not seven, as one of the reasons Hermione is so far ahead of everyone in her first year is fully explained... A September birthday gives her a leg up.

This story will be irregularly updated, as it is a fun diversion for me, and an interesting exercise as I attempt to match much of the story's style to Rowling's while going a completely different direction at times. She has a really unique voice that is just fun to write and mimic.

Also… I've done background research on a number of the subjects of this story for other works and will incorporate it as I see fit. After all Philosopher's Stones are cool things and Nicholas Flammel is a real historic person… and French. There's lots of other things which will be explained: Grindelwald's link to the World Wars, the Ministry of Magic's link to the muggle government, and some other amusing things I've stumbled on or thought about over the years. The explanation of some of these things will, hopefully, blow your minds.

One World

Part I: A Hidden World

Chapter 1: Godric's Hallow

Mr. and Mrs. Granger were well-educated members of the middle class, though they hardly gave that fact much thought as they drove along the road in their rather worn 1976 Saab. It wasn't something that mattered to the two of them. They weren't exactly the sort of people to become involved in anything mysterious or magical. In fact, most would find them amusingly mundane at first meeting them.

Of course, appearances can be deceiving, and fate has a tendency to amuse itself by casting average people into extraordinary circumstances.

It was late, nearly midnight as they drove into the outskirts of another sleepy village on the way to the M3 after their most recent dental conference visit and Mr. Granger's mind was focused on the troublesome case of Mr. Edwin Borger's wisdom teeth, which had begun to emerge from his jaw at the ripe old age of ninety.

A brilliant flash of light lit up the sky before them and Mr. Granger slammed on the brakes just as a large timber fell in the middle of the road. In the car seat behind them their toddler, the precocious two year old woke with a start and howled in fury.

"Bloody hell." Mr. Granger said as roof tiles fluttered down into the street and he gaped in shock. "Dear?"

"Shh… Hermione, it's alright." Mrs. Granger said as she twisted in her seat and tried to comfort the girl. "Calm down… Daniel, what was that?"

Mr. Daniel Granger shook his head nervously. "I don't know… dear." He stared out the windshield and gaped.

A cottage stood by the side of the road, half its roof blown away from some explosion. He put the car into park and swallowed. He could have sworn it hadn't been there before. "Dear…"

Mrs. Granger looked up. "Was… was that there before?"

"I don't know." He shut off the ignition. "We'll wait for the police, we're witnesses."

She nodded before the two parents froze in the car. Barely audible over the wind and creaking of the damage structure was a cry. A cry any parent with a heart would find unbearable, the wail of a child in distress.

"Dan…" Mrs. Granger said quietly.

He nodded and pushed open the door. "I hear it too… the glove box, there's a torch in the glove box."

Mrs. Granger pulled the torch out and handed it to him before glancing nervously around the street. "I… I've got a really bad feeling dear."

"Stay with Hermione." He said before thumbing on the torch and stepping from the car. Glass and bits of wood crunched beneath his feet as he walked toward the door. The brush of something in the bushes drew his beam and a rat with tattered fur scurried between the pickets before bolting into the street.

Dan swallowed. "Okay…" He stepped up to the door and it swung open with a slight push. His hand groped for a light switch and found none. "Hello?"

The child's wails overhead redoubled and Dan scowled, he swept his beam around the entryway and furrowed his brow. Then he froze as the beam landed on a pair of shoes. Daniel stared, his heart suddenly in his throat as he looked down at a dead body of a young man with round glasses, wild black hair and pale blue eyes. A stick of varnished wood lay in his hand and he had the strangest blank stare. Dan bent down to feel for a pulse then drew his hand back. He was cold and very clearly dead. "Oh bloody hell."

"Dan?" His wife called from the car.

Daniel Granger wished he'd listened to his wife when she pushed him to get one of those big new cellular phones for the car at that moment and swore under his breath. "Jean, stay back! We're definitely going to need to talk to the police."

He straightened up and glanced up toward the stairs where the child's cries were coming from. Slowly he stepped up the stairs, pushing aside fallen timber and refuse. Strange things were painted on the wall as he entered the first room he found. He could see a golden ball with glimmering wings, and swore they fluttered. There was a boy riding a broomstick looking as if he was chasing the ball.

An enormous hole had been blasted in the roof just beside the cot in the room, and he could see what looked like a black robe lying in a puddle before it. Bits of the roof covered the cot as he stepped toward it. Then he saw her.

A woman with bright red hair and green eyes that glittered like emeralds was staring unblinkingly up from the floor. Her front was covered in splinters from the explosion and he knew she was dead, from the look of it she'd died from whatever had ended her husband's life.

A sniffle came from the cot and Daniel cast his light on it. "Hello?" He pushed aside a pile of timbers and froze.

There, sitting in the center of the cot was a boy with his father's wild black hair and his mother's emerald eyes. Aside for a scratch shaped like a lightning bolt, he looked completely unharmed. Still his eyes were filled with tears and Daniel felt his heart break at the shell-shocked expression on the child. "Hello…" He said before reaching into the crib and pulling the child out with a blue blanket. He held the small boy to his chest and swallowed. "Do you hurt anywhere?"

The boy shook his head.

"What's your name?" Daniel asked and when the boy didn't respond added. "My name is Daniel Granger… what's yours?"

"'arry," the boy said.

"Harry?" Daniel asked and when the boy nodded, Dan smiled faintly. "Well then, it's nice to meet you." He carried the child down the stairs and felt him cling tightly to him as he saw the body of his father.

Daniel swallowed. "Jean!"

His wife looked up and stared at the child. "Dan… what, what did you find?"

"It's a mess… both his parents are dead, maybe hours ago from how cold they were." Daniel said as he handed the boy over to her. "We need to go to the police. I don't know why they haven't showed up yet."

Jean gaped at him for a moment before biting her lip. "His parents are gone?"

Daniel nodded as he pulled open the door and climbed behind the steering wheel. Jean held the boy as she sat down in the seat beside him. "Poor boy…" Jean said before carefully cradling the child.

He put the car into drive and quickly reversed heading back into the heart of the village. He didn't notice the giant of a man land just outside the cottage's picket fence holding a glowing old boot. His name was Rubeus Hagrid.

He looked up at the smashed remains of the cottage and immediately lost all thought of complaining about the impromptu mission for the Order. His jaw worked furiously as he stared at the remains of the cottage.

"Gallopin Gargoyles… Lily, James!" He headed for the door and crouched to peer inside as the rumble of a motorcycle echoed down the lane.

The giant looked up as an old motorcycle dropped from the sky with a thud and rumbled down the street. With a screech, the motorcycle came to a stop beside the cottage and the driver scrambled out.

He was a man with long curly hair, a small black moustache and lean features. His black eyes were wide with fear as he stared up at the smashed remains of the cottage. "James!" He called before running toward the door.

"Sirius." Hagrid grunted before pushing aside the door. Sirius scrambled past him and pulled a wand from his pocket.

"Homenum Revelio," Sirius stammered and swallowed as two red arrows appeared around him. Tears began to stream down his cheeks. "Damn you…" He growled before stepping from the doorway and lighting his wand. Sirius froze as the dim light lit the corpse of the boy's father. "Oh… James… not you, not you!" He howled as he knelt down beside the man. Then he looked up toward Hagrid. "Only two… only two?" He scrambled up the stairs and froze at the top. His gaze flicked across the nursery and the pile of debris that had been cast off the cot. "Harry? Where's Harry?"

"He ain't there?" Hagrid asked. "But… Dumbledore told me to come get him, bring him to Surrey."

"Surrey?" Sirius scowled before waving his wand again and swearing. "Someone's been here… besides us, they took Harry."

"Who?" Hagrid asked.

A siren echoed from the street and the two of them glanced out the hole as police closed in around the house. Sirius gaped. "But… the house has muggle repelling charms."

"Broke with the Fidelius I gather." Hagrid said before suddenly turning on Sirius. "Yeh! Yeh led him to them! Yeh were the Secret Keeper!"

"It wasn't me!" Sirius howled. "Where is Dumbledore? I need to talk to him…"

"I ain't gonna bring yeh to him Black, if yeh weren't the Secret Keeper who was?"

"Peter! Peter was the bloody traitor… oh God, this is all my bloody fault!" Sirius howled again and glanced back out the hole. "We need to leave. The muggles will swarm all over this place."

"Fine Black, lets go." Hagrid said before grabbing Sirius by the scruff of his neck.

For Mr. Granger, this trip had already turned really quite strange and heart wrenching. The boy that slept fitfully in his arms wrapped in the simple blue blanket had lost both his parents, and for a still rather new father the thought of what he'd seen in the house was like a strike to his gut.

Mrs. Granger hung up the phone from calling their clinic's office and sighed before turning toward him. The four of them were in the local constabulary office waiting for instructions, and while the small boy seemed to be comfortable sleeping in either their arms, he woke with a start and shudder whenever anyone else tried to hold him.

Perhaps the child had not seen many people outside his parents, or perhaps he was just shy, but something about the way he clung to the two of them tore at them as little Hermione watched her parents, her bushy brown hair going every which way as she looked between them.

"Daddy, what are we doing here?" She said with surprisingly articulated speech for a two year old.

"We're talking to the police so we can find out what to do about young Harry." Mr. Granger said before smiling faintly at his daughter.

"Can't we take him to his mum and dad?" She asked before peeking at the boy in his arms. "What's that?"

"A scratch sweetie." Mr. Granger said before brushing the boy's bangs over the lightning shape scar. "Just a scratch."

"It looks like lightning, did lightning hit him daddy?" The girl asked quickly and Mr. Granger grinned at his daughter.

"I don't think so sweetie."

The door opened and a bobby stepped inside still clad in his bright yellow public safety vest and headed over to one of the desks. He tore the receiver from the phone and hurriedly dialed a number as the Grangers watched. "Village Clerk's office... yes, I need you to find the title to the land at the end of West End road, there's a cottage there and I need to know who owned it, right! Right! You say it's not in the system. Well check the files in the basement!" He snapped at the end and slammed the receiver down on the phone with a growl. "Idiot woman, I know what time it is." He glanced over at the couple with the child and sighed. "Mr. Granger?"

"Yes." Dan said as he rose carefully still cradling the child in his arms.

"I need to take your disposition..." The officer said before pulling out a pad of paper and clicking a pen.

"Right..." He stood for a moment and sighed. "I was driving along the West End road, heading for Devon... My wife and I were on our way back from a Conference in Winchester."

"Conference? What is your profession?" The bobby asked.

"My wife and I are dentists. I got a full ride for time in the Royal Navy. I'm a reserve now." He shrugged. "I met Jean, my wife, at school. We've been married for five years now."

The bobby nodded. "Alright, what time do you think it was?"

"Around midnight, maybe five or ten minutes till." Dan said still cradling the child. "I saw a bright green flash and timbers fell into the street. I stopped my car after swerving to avoid them and saw the cottage... it looked like shell or bomb had hit the roof. Boards and tiles everywhere and... We heard, wailing from inside."

"The boy's?" The bobby asked still scribbling his notes.

"Yes... I stepped out and went to find the child. I found a man, stone cold dead in the entryway and a woman upstairs. From their appearance I think they were his parents." Dan said as the child clung to him in his sleep. "I... I went ahead and pulled the boy from the rubble... it looked like something exploded next to his cot and the roof fell on it. It's a miracle he just got away with a scratch."

"Yes, well..." the bobby glanced at the boy."What did you do next?"

"Came here to report it." Dan sighed. "What'll happen now?"

"I don't know... but first we need to identify the child. Did he tell you his name?"

"Harry." Dan said quietly.

"Alright," the bobby said before underlining the name three times. "Harry."

The phone rang again and the bobby snatched it from the hook. "Inspector Williamson, that's right? James Potter, you say. Did you find any records of the man in the system? No... shite. Any references to a Harry Potter in the records? Check for birth certificates, anything? I'll have the coroner try and ID the Jane Doe." He set the phone down and sighed. "Damn."

"Nothing... what'll happen if you can't find any relatives of the boy?" Mrs. Granger asked.

"He'll be sent to child services and probably end up in a home," the bobby said quietly.

"A home? He's only a year old, at most." Mrs. Granger chewed her lip and pushed some of her wild and curly hair from her face. "Surely there's someplace or something..." Dan glanced at her as she quieted and swallowed as he recognized the intense expression on his wife's face as she stared at the boy. "What if..."

"Dear?" Dan swallowed.

"What if we took him, at least until you found relatives for him to stay with or..." Mrs. Granger glanced at Hermione who was staring at the boy curiously. "Could we adopt him?"

Dan gaped. "Jean? I thought... I thought you didn't want another one."

"I couldn't leave him with the police..." She said quietly and bent down before Hermione. "Sweetie... would you like a little brother?"

As the girl nodded, Dan felt himself swallowed and glance at the boy. "We... we'll need to move, the house isn't big enough for two of them."

"Mr. Granger..." The officer said quietly. "If you'll take guardianship of the boy, if... if you don't hear from us in thirty days it'd be safe to assume we haven't been able to find any relatives of the child, and he'll be yours to adopt. I'll see about getting the paperwork."

"But..." Dan glanced at his wife and daughter before letting out a sigh. "Fine."

No one in the Godric's Hollow police station that night would understand the relationship between the boy and the strange happenings of the following day. The fluttering of owls in broad daylight, the meteor shower over Kent, or the celebration of thousands of strange folks clad in robes and cloaks throughout the whole of the United Kingdom.

When they drove home the following morning they had no idea that a desperate search was going on around them for Harry, the small boy who Hermione had taken to fuss over like a little doll, or that there were toasts being made to Harry Potter's sacrifice and the end of a dark wizard called You-Know-Who.

For Sirius Black, it was a personal struggle against two violently divergent desires. One was a desperate need to hunt down the rat who had betrayed his best friend and the other being a feral desire to find his godson. As he sat in the familiar chair across from the desk of the Headmaster of Hogwarts, the man was on the verge of tears.

Across from him was a wizard who looked every part the muggle image, his beard was long and ghostly white and he wore robes of midnight blue decorated with half moons and stars. A cap topped his head and he wore a set of half-moon glasses over which he peered at Sirius.

"Young Harry Potter must be found... while the rumors circulating the wizarding world talk of his heroic sacrifice. My instruments indicate that the boy is not dead." He glanced at Hagrid who was standing beside the distraught Black then turned to Minerva McGonagall. "Nor is Lord Voldemort."

"Can you detect his location?" Minerva asked quietly.

"No," Albus said quietly. "My attempts as scrying have failed, perhaps he is under wards or other protections, though if he survived by the means I believe it may be only a byproduct." He glanced at Sirius. "Either way, we must clean up the mess at Godric's Hollow. The muggle authorities are no doubt desperately trying to discover how a cottage appeared in the middle of their town. Bathilda has told me that they have been removing bags of evidence from the home and are being very thorough with their search. We cannot allow our world to be revealed at this juncture. Sirius and Minerva, I want you to go to Godric's Hollow, recover what you can, obliviate the memories of the muggle police and see if you can find anything to point yourself in the direction of the young Harry."

"Yes headmaster." Minerva said quietly as Sirius nodded dumbly and stumbled to his feet. After a moment, he walked to the fireplace and the flames shot up, burning bright green before the two of them stepped through.

Sirius stumbled out of the floo into the middle of the Three-Broomsticks as Minerva stepped gracefully up beside him. She glared down at him as he shakily clambered upright.

"Sirius! How are you?" Madam Rosemerta, the barkeep shouted. "Can I get you something?"

The Three Broomsticks was packed with patrons and revelers. Sirius glanced around and glared at the barkeep. "Nothing, just passing through…" He growled out.

One of the nearest patrons turned to him, "What's wrong with you Black?"

"What's wrong? My best friend is dead!" He snapped back and ran a hand through his wild hair before closing his eyes and taking a deep breath. "It's all my bloody fault."

"Sirius…" Minerva said quietly as the eyes of the crowd were on him. Sirius turned toward her, and faltered under her stern gaze.

"I asked them to make Pettigrew the Secret Keeper. I may as well have led Moldyshorts there myself." He gasped for breath as Minerva's stern expression melted. "I need to find Harry, I owe them that much... then I'll find Peter and kill the son of a bitch."

"Sirius... let's find Harry first." Minerva said before glancing around the celebration and giving a sniff of disapproval. "Celebrations..."

"There's nothing to celebrate." Sirius growled before nodding to Minerva. "Let's get out of here."

Spinning once, he disappeared with a pop of displace air and reappeared in the center of Godric's Hollow. A moment later, Minerva appeared beside him and waved her wand transfiguring her clothes into something resembling a muggle's choice of clothes.

Sirius headed down the street gripping his wand, it was time to get to work. After going around a hundred yards, they found the house.

It was worse seeing the damage in the morning light, the smashed second story stood out in his mind as he glanced at the yellow tape the muggles had drawn around the home and the two uniformed officers talking in low whispers as the approached.

"Robert, I don't get it either, I could have sworn there wasn't a cottage here... and I've lived here all my life." The older of the two police said under his breath. "The investigators are all asking questions about it and I can't tell them a straight answer..."

Sirius glanced to the side and saw Minerva morph from the stern faced professor into a thin tabby cat. A tabby that had rather distinctive markings around its eyes that reminded him of her spectacles. The cat slipped through the picket fence and into the house as Sirius watched.

Then he glanced back at the two police and took a deep breath before shoving his wand out of sight beneath his cloak. Perhaps all those years taking Muggle Studies to piss off mum would bear some fruit, he thought to himself.

"Morning officers." He said.

"Hello." The younger of the two said before stepping toward him, staying on their side of the yellow police line. "I don't remember seeing you around, you new in town?"

"Nah... Just passing through. What happened? Looks almost like an explosion went off." Sirius asked after looking up at the house for a moment.

"Don't know... haven't found any cause for the blast, some dentist from Devon or something reported a green flash last night when he was driving through." The officer shrugged. "Green like a firework or something, you know."

"Really?" Sirius said before chewing his lip. Green spell fire was a sure sign of a killing curse being used, but an explosion? That was unusual. He felt his gut turn cold as he thought about it. "What else?"

"Well... the dentist see... he went in and found a little boy inside, bout one or something and took him to the police station with him to report it. I think the chief helped him with some paperwork to be the kid's temporary guardian till some relatives could be found. The lad's parents... well, they're at the coroner's office, both stone cold dead. I've never seen anything like it, not even a scratch on one of em." The policeman shrugged. "We've been finding weird stuff in the house, taking it to station... something really strange about this place. It wasn't here yesterday, like something out of a fantasy novel or kids story..."

"You don't say." Sirius said as he tightened his grip on the wand and focused on the two of them. "Well... that is strange."

"Yeah..." the policeman glanced at his partner." Don't know what all to do about it... only thing we found was a deed to the house on file, but not in the computer system, they just started using. Very strange you know."

"Very." Sirius twisted the wand in his hand and whispered "Obliviate." The man's eyes turned cloudy for a minute before Sirius flicked his wand toward the second partner. "Obliviate."

"Now... neither of you remember anything odd about this house or its location." Sirius grunted before banishing the police line and striding toward the house. He lifted his wand and began to cast a muggle repelling charm over the home. When he finished he stepped into the house and swallowed. "Minerva..."

The old professor appeared at the top of the stairwell, her normally stern mask shattered as tears had begun to run down her cheeks. She swallowed from where she stood and shook her head. "Oh God Sirius... it's horrible. I did a trace charm... three killing curses in the house... one by the door, two up here by the cot."

Sirius nodded as he climbed up the stairs. "I didn't have time to... three you said? But... the policeman said a dentist pulled the boy from the rubble. Harry... couldn't have survived, could he?"

"I do not know... Albus said the boy was alive from his instruments but." Minerva took a deep breath and steadied herself. "Lily and James... could they have found some way to block the curse?"

"I don't know..." Sirius said as he glanced around the room. "I restored the muggle repelling charm." He glanced around the room felt a tear roll down his cheek as he saw a small toy broom in the corner, apparently untouched. He walked over and picked it up gingerly. "I gave Harry this..." He said quietly before turning to Minerva. "Three months ago, on his birthday."

"You... you can return it to him, once we find the boy." Minerva said before heading down the stairs. "Did you find out where the muggles took their bodies?"

"The coroner's office apparently." Sirius said quietly. "Minerva, they've been taking things from the house... as evidence. 'Strange things' the officer said. If it could lead back to our world..."

"We'll have to recover them." Minerva said before taking a deep breath. "Albus would say it was more important than their bodies."

"I know... but we'll get them to." Sirius said as he headed back out onto the street. "We'll go to the police office first then."

It wasn't a long walk to the police station, and as the two of them stepped inside Sirius felt strangely at home with the cubicles full of papers and officers grabbing at phones. After a moment, he realized that replacing a few things in his mind with their magical equivalents and he was standing in the village's Auror office. He saw that only two officers were on duty and guessed that a town like Godric's Hollow didn't require a large force.

"I'm sorry. It's been a long night. Can I help you?" The officer behind the desk asked.

"I think so..." Sirius said as he leaned against the cubical. "I have some information about that boy you found last night."

The officer's eyes widened. "Really?"

"Yeah... have you had any luck identifying the parents?" Sirius asked conversationally.

"Unfortunately not... considering the deed we found in the clerk's office we've identified the John Doe as a Mr. James Potter, but we can't confirm it... still no clue on his wife. It's like the pair never bothered with a driving license or government paperwork at all." The officer rubbed his temples. "The dentist that found him signed papers to be the boy's temporary guardian."

As Sirius talked to the officer Minerva slipped behind the desks in the form of a cat and began to explore the office.

"Anything unusual about the boy?" Sirius asked.

The officer shook his head. "Nothing really... he had a scratch from the debris that fell on him... shaped like a lightning bolt but beside that, not really anything springs to mind."

"Thank you." Sirius said before lifting his wand. "Obliviate!"

The officer's eyes went cloudy before Minerva transformed and obliviated the second policeman on duty. Scowling to herself, she began to sort through the papers looking for anything about the case, any records.

Sirius leaned over the desk and found a muggle legal pad filled with notes on the case. He ripped out the relevant pages, folded them and stuffed them in a cloak pocket. "I got the detective's notes."

"Good... I think I found their official records and modified them." Minerva glanced around the office. "Is that the evidence room?"

Sirius nodded and pointed his wand at the lock. "Alohomora." Then he pulled open the door. Minerva began to search shelves as Sirius pulled a clipboard from the wall and scanned it quickly. "According to this their case records, the evidence will be on shelf 13B."

Minerva nodded and pulled three large crates from the shelf and opened the boxes one at a time. Inside each were magical tomes, wizarding photos, and other clearly magical items. With a wave of her wand, she shrunk the boxes and pocketed them. "Now... the coroner's office."

Sirius nodded and headed out the door. He didn't notice that the last page of the legal pad he'd ripped the pages from held a telephone number and a name.

Miles away the Grangers were stepping up their drive with their newest addition to the family. The group slowly spread out through the two-bedroom house and Mr. Granger rolled out a sleeping bag for the boy. At that moment, he knew they'd have to move, but then Jean had already talked about moving to another town. She'd always said she'd liked Winchester.

As the small black haired boy snuggled against a pillow in the small cot, he had no idea that thousands were toasting his name in Wizarding Britain and a handful grieved for his parents. He did not know that Sirius Black would soon begin a desperate search for a Daniel Granger of Devon and come up empty for the next nine years.