A/N: I wanted to read a good Harry-has-a-twin-who-is-mistaken-as-the-bwl but I can't find one with ALL my favourites... so I'm writing one. Don't complain. It's probably not very decent, but still...
Warnings: Filled with cliches, slash, Dumbledore bashing, GOOD!Voldemort, starts during first year and flashbacks to other times(flashback at beginning of each chapter), tossed-aside canon(blood-magic haha).
Cliches: Powerful Harry, Brat twin, Dark Dumbledore, Good Voldemort(is that cliche?), HEIR!Harry, Fatherfigure!Remus, neglectful!Parents(not abusive).
Pairings: SiriusxRemus, Eventual DracoxHarry, SeverusxRegulus, JamesxLily, ChoxCedric(eventual), RonxHermione(eventual), NevillexLuna(eventual)
Summary: When Harry started being ignored in favour of his younger twin, Remus began taking care of him.
Disclaimer: I own absolutely nothing, not even the plot.
"I give you Aidan Potter, the boy who lived!"
Everyone let out a loud round of applause, and the parents ran over to Dumbledore and Aidan. Sirius ran over to his godson, a proud grin on his face. Remus, on the other hand, turned his gaze to the smaller but older child, left abandoned on the floor.
The child, Aidan's older twin brother, was nearly opposite of the younger. While Aidan had fiery straight red hair, deep hazel eyes, and nicely tanned skin, the elder-Harry-had messy black hair, killer-curse green eyes, and pale skin. It was naturally pale-no amount of sunlight seemed to change that.
There was another difference, Remus noted, not just with their magic levels, but with the scars on their foreheads. Aidan had a dark red-bleeding, a voice inside Remus' head whispered-- sun-shaped scar that looked suspiciously a lot like what hung above his head before the magic fire. Harry had a thin lightning-bolt shaped scar that had no signs of bleeding.
Then there was the magic, Remus thought, ignoring his friends' cheering as he picked Harry up. Harry's magic was nearly depleted, but it was strong, while there wasn't even a dent in Aidan's. (Remus had a natural magic-detecting talent-he'd always just assumed it was due to his lycanthropy. Either way, there was something wrong with the picture.)
He looked up again at the crying, bleeding Aidan, to the cheering parents and godfather, back to the forgotten silent child. Dumbledore was wrong, Remus knew, but he didn't say anything. He knew he couldn't change their minds.
Dumbledore's pride wouldn't stand for it.
Remus smiled at Harry. Even if his friends ignored little Harry, he never would. Even if Harry hadn't been the true savior, he wouldn't walk away from the child. Not when he needed him.
Harry opened his eyes seconds before his alarm clock went off. He jumped out of bed and bounded over to his closet to grab his dress robes. It was his and Aidan's birthday, and even though his name was absent from the "Happy Eleventh Birthday!" banner and cake, even though he had no presents piling up in the corner, even though the party wasn't for him, he was still excited.
"Uncle Moony said he'd take me to Diagon Alley to get my things," Harry grinned to his cat. The cat, Ginger, was an old orange cat, lazy as could be. Ginger was a toss-off from Aidan, who had wanted an excited, eager cat like his Gryffon-that was his gold and black coloured cat that he'd gotten after handing Ginger to Harry. Sure both cats were old by their eleventh-they got the cats when they were five!-but Harry still loved his.
"Since Mum and Dad will be too busy with the press and all," he mumbled, tugging his robes on and running downstairs to breakfast. The messy-haired boy grinned when he saw Remus was already there. "Hey Uncle Moony!" he greeted, sitting at his spot. He didn't greet his parents-they didn't notice him anyway. "When can we go to Diagon Alley?"
"We have to wait for your letter first," Remus told Harry, smiling.
Harry was nearly jumping up and down in his seat by the time the letters came. The owl dropped one letter in front of Harry and another in front of Aidan, and Remus congratulated Aidan before turning to Harry-who was, once again, unnoticed by his fawning parents. "Now we can go," he chuckled to the excited child.
-At Diagon Alley-
"We'll get your wand last," Remus told Harry, smiling. "First let's go get some money from the bank."
The duo headed towards Gringotts, where Harry insisted on them getting money out of the Potter family vault.
"What's the young master's name?" Griphook asked Harry, looking at a document that Harry was sure had a list of names of those allowed to access the vault.
"Harry Potter, Sir," Harry answered without hesitance. There was a moment of complete silence.
"There is no Harry Potter on this list," Griphook said at last. Harry looked genuinely surprised.
"What? But there has to be a Harry Potter. I'm the Potter heir."
"It says here that Aidan Potter is the Potter heir," Griphook replied gravely. It was a shame, really; Harry was such a nice boy, and Griphook truly liked the boy. But no Harry Potter had permission to access the vault.
Remus understood well what had happened, though. James had Harry disowned so that Aidan would be the family heir. The werewolf's fist clenched slightly. "It doesn't matter," he told Harry. "We'll just get some out of my vault-"
"You can't afford that, Uncle Moony," Harry said quietly, looking a little upset. Then he turned to Griphook. "I have a few galleons with me from my birthday today-" galleons that Uncle Moony gave him... "-so could I open a vault?"
Griphook was silent again. "Would you rather have a blood test to see if you are heir to any of the ancient vaults or magicks? Rightful heirs who are disowned can become heirs to any of those vaults or magicks. Of course they must be born into it, but it is a great curiosity."
Harry glanced up at Remus, who simply shrugged. "Well... sure," Harry nodded, a little unsure. Griphook stepped down from his podium, and immediately another goblin took his place to take over his work while he was absent.
They followed the head goblin into a room in the back. Honestly Harry wasn't expecting much, but Remus had no advice against such an adventure.
Harry and Remus both did as they were told-Remus i a chair off to the side, Harry right in front of a basin with a piece of parchment inside. Griphook took out a knife-small and sharp, perfect for its job.
"Hold out your hand and stay still."
Again, the elder Potter-or was it ex-Potter?-did as he was told, holding his hand out to the goblin, who carefully pricked his finger. Harry winced only slightly, but let the blood collect at his finger tip.
"Let it fall in the basin now."
Tipping his finger slightly, Harry watched as the blood slid from his finger tip into the basin. The blood spread out when it hit the water but sunk into the parchment.
After a few moments, Griphook peered into the water. His eyes widened very slightly, the only bit of emotion Harry had ever seen from the stoic goblin.
"This is amazing," Griphook mumbled. "I had thought maybe so, the vaults all became active soon after you were disowned, but I never imagined..."
"What is it?" Harry asked as politely as he could in his curiosity. Griphook looked at him and gestured to the basin.
"Look," he commanded, and Harry did. The parchment read;
Son of James Potter, Lily Potter nee Evans
Brother of Aidan Potter
Godson of Remus Lupin
Disowned [Third of August] 1982
Aged  current
Hogwarts House Unknown
Heir to  vaults
Heir to  families
Inherited  magicks [Elements]
Heir to; Slytherin, Gryffindor, Ravenclaw, Hufflepuff, Merlin, Morgana, Riddle Vaults
Heir to; Gryffindor, Merlin, Riddle family
Inherited Magicks; Fire, Water
Magickal core; Ignis et Glacies [Flame and Ice]
Animagus Form; Corvus [Raven]
Familiar; Ninetailed Fox
Harry stared at the parchment, eyes wide. Never had he imagined such an extensive list. "There has to be a mistake here," he declared, looking at Griphook.
"The parchment doesn't make mistakes," Griphook informed Harry. "You are undoubtedly the heir to all of these vaults, those families, and those magics. Now you just need a proper trainer."