Disclaimer: It's all JKR's. Always.
It was a bright, sunny summer's day in Diagon Alley, and Harry Potter was on a mission. He didn't stop in Quality Quidditch Supplies, didn't look in the window of Fortescue's, and didn't even look in the direction of Flourish & Blotts' (not that the latter was particularly a temptation). He kept his eyes on the large marble building at the far end of the alley: Gringott's.
Harry swept into the wizarding bank in a very Adult way, but before the door had even closed behind him, he deflated, and made his way as quietly as possibly across the marble floor. Gringott's had that effect on people, rather like a library; probably because goblins have as much respect for Galleons all gathered in one place as wizards do for books. Only Galleons are less likely to try and bite.
An imperious looking goblin (albeit, 'imperious looking' is a phrase that could be used to describe most goblins, and so wasn't a particularly defining feature) gestured for Harry to approach his desk, and Harry fumbled for his vault key, deep in his pocket.
"Harry Potter, just here to check the tally of contents of my safe," he said, handing over the key for goblin inspection. The goblin frowned as it checked the key, but, as he handed it back over without complaint, it appeared everything was acceptable.
"I'll have to go and find your record," the goblin said, sounding terribly put out by the whole affair. Harry had to bite his lip to stop himself apologising.
The goblin disappeared for several minutes leaving Harry to twiddle his thumbs, although rather unsuccessfully as he wasn't entirely sure how it was supposed to be done. The goblin eventually returned with a rather large and exceedingly dusty tome, which he dropped on his desk with a resounding thud. He quickly rifled through the pages, before finding the entries he was searching for. Harry leaned forward, hopefully.
"Your last withdrawal was at Easter, Mr Potter, and since then your interest for the tax year has been calculated and paid, and the quarterly trust fund payment made."
"Trust fund payment?" Harry asked, with Suspicion, although less surprise than one might have thought usual under the circumstances.
"Of course. Our orders regarding payment into your account from the main Potter account are fully complied with, I assure you."
"And, eh," Harry hesitated, finding thinking and speaking at the same time a troubling task, "whose orders are those, if you don't mind my asking?"
"Your parents'. They left explicit instructions in their will as to how much money was to be paid to you on the occasion of their death," the goblin answered defensively, looking suspicious.
"And who was the main benefactor of that will, who now oversees the payments into my trust fund?" Harry asked, although he thought he knew the answer already.
"Professor Albus Percival Wulfric Brian Dumbledore, of Hogwarts."
"Thank you," Harry said, channelling all of his Adultness, "That will be all today."
The goblin muttered something, most likely unflattering, in Gobbledegook that Harry didn't understand, but disappeared with the ledger without overt complaint. Harry turned, and made his way out of the wizard bank.
So. Sirius' will had been changed to benefit Dumbledore and the Order, the occasion of which the lawyer was fuzzy about. The Potters' had also left their fortune to the Professor, rather than their own son. It seemed like some dodgy dealing was going on: and with Harry at the centre of it. Why was Dumbledore trying to hard to keep Harry from his rightful inheritance?
The answer, he hoped, lay at his next appointment.
Harry quickly made his way back down Diagon Alley towards Eeylops' Owl Emporium. He had spent some time working out which shop would be the least likely to see a visit from either Ron or Hermione, which, considering the vast differences in their shopping habits, was a very short list to choose from. But the Emporium seemed the best choice.
He slipped in between the rows of gently cooing cages until he reached the back corner of the store, where the toads were kept. Being a rather unfashionable pet, it was a very secluded place, which was perfect for a clandestine meeting.
"Afternoon, Potter," came a familiar voice from behind him. Harry turned to see, oddly enough, the very person he had planned to meet.
"Mundungus Fletcher. Thanks for coming," Harry said with a slightly forced smile, the smell of tobacco and alcohol so strong it made his eyes water. The nearby toads began to look as though they had been poisoned.
"Don' mention it, don' mention it. Task like this is much more me sort ov fing than fightin' bleedin' Death Eaters."
It was a risk asking for help from Mundungus Fletcher. His morals, courage and personal hygiene aside, he was also extremely loyal to Dumbledore. But Harry was hoping he could work around that, as long as Dung didn't recognise how thoroughly Suspicious of Dumbledore Harry had become.
"So, Dung, what did you find?" Harry asked, hiding his impatience masterfully.
"Awright, then. The Black inheritance consisted ov a vault full ov gold an' jewels an' the like, the 'ouse at Grimmauld Place - which did not originally come wiv a set ov silverware, by the way, no matter what that bleedin' 'ouse elf says - and the Island ov Azkaban an' the rent that takes in, plus the Black family seat on the Wizengamot an' the title ov Lord Black, Earl ov Azkaban. All ov it now belongs to Dumbledore, an' the lawyer is pretty fuzzy about 'ow that came to be the case."
Harry was Surprised. The vault of gold and Grimmauld Place he had expected: but seats on the Wizengamot? And the Island of Azkaban? Sirius owned the very prison he'd be locked in for twelve years? It was horribly ironic.
"What about the Potters' will?" Harry asked, keeping his expression blank. He had a feeling he knew what Dung would have to say on this, too, but he squashed down his emotions. He was, after all, an Adult.
"The Potters left evryfing to you, lad, an' the lawyer seems a bit fuzzy on why it's been left in trust. Right now, you get a stipend, an' the main vault, plus Potter Manor an' the seat on the Wizengamot an' the title of Sir Potter, Marquis ov Peverell, are under Dumbledore's control."
Harry nodded. His Suspicions appeared to be correct.
"Oh, an' on top ov all that, I done some more diggin', and turns out you're also the Heir of Squigwiffle. Ain't that somefing?"
Harry was Gobsmacked. The Heir of… who now?
"What's a Squigwiffle when it's at home?" Harry asked, perplexedly.
"Well, I wasn' all that sure an' all, but turns out 'e was the fifth founder of 'Ogwarts!"
The fifth founder of Hogwarts? This sounded like a rather unrealistic sort of plot twist to Harry.
"Turns out there was five ov 'em, but ol' Squigwiffle drew the short straw, lit'rally, and didn' get one ov the four towers to start an 'Ouse. Even though 'Ufflepuff moved down near the kitchens to better cope wiv 'er constant munchies, and Slyverin down to the dungeons so 'e could better pet that giant snake of 'is in private, they wouldn' let Squigwiffle 'ave one. So 'e went in an 'uff, an' built 'is own 'ouse at the end of the road by 'imself."
Harry began to put two and two together, albeit it had been years since he'd been in a Maths classroom and he wasn't quite sure he could remember how.
"So I own the Shrieking Shack now, do I?"
"The 'ole of 'Ogsmeade, more like, lad! Although you don' strictly own it as yet - ol' Dumbledore 'as that one on trust for you an' all."
"So I could be Lord Black Sir Potter, Earl of Azkaban, Marquis of Peverell, Heir of Squigwiffle right now, if things had been ever so slightly different?"
Like if Dumbledore wasn't a gold digger, different.
"Well, thanks for this, Dung," Harry pretended to be calm, but his mind was already racing ahead. The things he could do if he had that kind of power and influence! The Ministry would never dared have treated him like a liar, and he wouldn't have that scar on the back of his hand. He could have enough power to properly oppose Voldemort, rather than hiding away from him, scared all the time. What was the in the prophecy about a power the Dark Lord knew not?
"If you hear of anything else regarding any of these legacies, you will let me know, won't you?"
"Course," Dung said with a grin, and he stretched out his hand. Harry dug into the pocket of his jeans, and pulled out a rather large (numeratively, rather than physically) cheque, which Dung stashed greedily in the depths of his robes.
"Nice doin' bus'ness wiv you," he grinned, then promptly Disapparated with a loud crack.
Harry Potter had some thinking to do.