1995
It didn't occur to Sirius that there was a way he could protect his godson without working with Dumbledore until the Goblin manager that oversaw his vault's matters suggested it to him.
It was to be noted that Dumbledore was not in Sirius Black's good book for a few years now. After all the many inaction and the things the man had done to Harry and to himself, he couldn't bring himself to blindly trust the defeater of Grindelwald that was Albus Percival Wulfric Brian Dumbledore. Sirius just knew that in his heart that he would be a fool to put even the slightest bit of hope that that despicable man would earnestly aid him.
Around one year ago, just before Harry and Hermione came to rescue him, Dumbledore had suggested not-so vaguely for him to fly to another country. Even then, Sirius hid it from the man that he didn't actually fled the country. Again, there was not much trust and faith Sirius could put in the older man, not after what Harry had endured because of Dumbledore not doing the right thing to at least put Harry in a loving household. He had seen Harry ― vulnerable, naive, trusting, and... tragically love-depraved. Harry was so trusting and naive, and didn't think for even just one minute before accepting Sirius' offer of a different home ― and that was evidence enough. After all, Sirius Black was literally a stranger to Harry and Harry shouldn't just say 'yes' so desperately if Harry was happy living with Lily's sister's family.
Yes, Sirius wanted to prioritise Harry's happiness, first and foremost. As Harry clearly hadn't the happiness Sirius wanted him to have, he directed all his frustration, and somewhere along the line, it turned into hostility, at Dumbledore who had taken Harry away from him that night via Hagrid. If the man bothered to do such a thing as taking away a child from his supposed guardian (was it kidnapping if said guardian gave reluctant permission?), why didn't Dumbledore ensure that Harry was happy under those Muggles' care? After all, it was that filthy wanker by the name of Albus Dumbledore that had the bright idea to put Harry under those bleeding Muggles' house and that automatically made him responsible for Harry's well-being. Yet, Dumbledore did... absolutely nothing and instead kept forcing Harry to return to the Muggles' care.
Sirius would and could never ever forgive Dumbledore. Never he would ignore the fact that Dumbledore could do better than that poor excuse of a Muggle family. Like a good, rational Wizard that he was, Sirius assumed the man had to have reasons for putting Harry in Lily's sister's loving care, but no, he he didn't give two shites about it. Whatever reasons Dumbledore might have, they must be incredibly rotten as nothing would really justify forcefully putting a child in a loveless (maybe abusive?) household.
Now that Voldermort, the so-called Dark Lord (ah, yes, Sirius could sometimes thought or said 'the Dark Lord' when referring to Voldemort, as his late brother, Regulus, was especially keen on him staying safe and that meant not carelessly or thoughtlessly saying 'Lord Voldemort', a likely fake name, even in his thoughts and saying You-Know-Who or He-Who-Must-Not-Be-Named was too distastefully long and mundane in everyone's general opinion, so now and then Sirius did call the bastard 'Dark Lord') was one-hundred-percent back, Sirius was practically on his feet, ready to take Harry away from Britain at any moment. But Dumbledore had owled him in time and told him to help Remus (who'd do anything for Dumbledore, which was grating Sirius' nerves now) gather the 'old crowd' and if he could, to prepare a safe house for the said 'old crowd' to have a meeting place ― preferably a house with the House of Black's famously impenetrable wards. The bastard obviously knew Sirius had inherited Uncle Alphard's gold, flat, and house.
Sirius was really, really contemplating of refusing all Dumbledore's demands. Just who did Dumbledore think he was, anyway? He was absolutely chuffed indeed at being told what to do by someone he didn't have much respect for. But sadly, Sirius realised, in order to be close to Harry, he had to stay in the Headmaster's good graces, or otherwise, Harry might be banned from ever seeing his godfather and Sirius didn't really want that, did he?
Throwing imaginary darts and knives at the man's smiling pic in his mind, Sirius scowled at the thought of one Albus Dumbledore getting in his way. He had decided since he stepped foot the Goblins' territory that he would ignore Dumbledore until he sorted things out. It was this or running to the headmaster's dwelling when the wretched man owled him yet again to tell him to lay low, preferably not near Hogwarts or near Harry and further than that, the 'have you prepared a safe house for us yet, Sirius?' inquiry and the 'also, you will have the Weasleys and a few more of our people as guests for the entire summer, just a heads-up' had set him over the edge.
He didn't want to hide. He didn't want to be Dumbledore's servant. All he wanted to be near Harry, to see if he was healthy, happy, well-fed and most importantly; safe. No, Sirius couldn't afford to nor did he want to be far from Harry, no matter the cost. He had failed him for twelve years, he wasn't going to continue doing so by running away from his duty again.
Now, he was visiting the Gringotts. After all, Sirius Black needed money and means to protect his godson. It was just so happen that the Goblins didn't care that he was a wanted fugitive.
"―I owe my godson a life debt. He saved my soul from being sucked by Dementors," Sirius told with reverence and pride to the Goblin before him.
He was unloading his stress on the poor Goblin, who was now acting like his consultant. Thankfully the Goblin wouldn't blab to anyone about this (one-sided) conversation because this meeting was confidential in nature and well, his vault had a great deal of money, so the Goblin wouldn't ever sold him out.
As he was babbling and talking his head's off, Sirius thought of the one time when Harry had saved him from a fate worse than death. It caused Sirius glow with a kind of warmth that was burning him inside. He concluded that it was love that he felt for Harry and something else. And so Sirius searched inside himself and felt it. He had a life debt to Harry. Oh, he was happy at the discovery, gleeful even.
Now he had even a greater reason to protect Harry. Even if Sirius didn't owe Harry a life debt, he would still try his damned best to find a way to protect Harry. The boy was his godson, after all.
"I'm really grateful, eternally grateful for what he'd done to save my worthless arse. So you see, I want to return the favour. But you know, Burgock, I just don't have the strength and the wit that I used to have before Azkaban. Plus, being a wanted man and all, I'm useless," Sirius rambled on. "If only there was a way to protect Harry from the Dark Lord, those Muggles, and that man without harming everyone, well, sans the Death Eaters and the Dark Lord, that is. It's frustrating that I couldn't even think of one―"
Burgock looked up in a mild annoyance. "―there is one."
Sirius ceased his rant. "Pardon?"
Without looking up, Burgock continued, "The question is; how much would you give?"
Sirius blew out an exaggerated sigh, knowing what the Goblin wanted from him. "Take sixty galleons from my personal vault. Is that acceptable for you and your kind's 'greed', Burgock?"
"Not acceptable by a long shot, but it's better than nothing. Very well, you will have my service." Burgock sniffed and turned to Sirius instead of inspecting the document in his hands. "Well, there is one way to protect your godson, Mr. Black. However, there is one issue."
"What kind of issue?"
"It'll irreversible unless one of you dies."
Sirius didn't even pause. He'd imagine that he would die earlier than Harry anyway. "Not a problem. What do you have in mind?"
"Magic and Soul Bonding Contract sealed with our magic, the Goblins' magic. A binding magical contract, a specialty of the House of Black." Burgock smiled, his eyes glinted oddly. "It just so happens that your grandfather had confided in me before his death. In regard to my former job as a Goblin Curse Breaker, he deemed me worthy and gave me the instructions with the condition that I tell only the one bearing the last name 'Black'. Yes, I am competent enough to make the contract. Did you know anything about it, Mr. Black?"
Sirius processed that before he let out a loud, "Uh, contract what?" He searched deep inside his mind until he found what he was looking for. He felt a chill passing through him for a second as he did. "Ah. That."
Yes, that. The Contract that every Black used to be able to share basically everything with someone, usually their spouse or someone they thought was worthy; including their magic, thoughts, pain, a unique skill, even lifespan (if given selflessly). But then something hit him like one of those crazy fast Knight Buses.
"So you know. Shall I send my partner to fetch the instructions from the Black Vault?" asked Burgock.
"Hold on. I could access the Black Vault? Mother didn't actually disown me?" Sirius grimaced.
Burgock blinked. "Of course you're not disowned. Whoever gave you the idea, Mr. Black?"
Sirius turned pensive for a moment. He drawled out with visible reluctance, "My mother, perhaps?"
Burgock stared like his client was out of his mind. "You're the sole male capable of carrying the name of your house. It's out of question for anyone with sanity to even consider disinherit you." Sirius scoffed softly at that. "Before she died, your mother stated in her will that she didn't want neither Bellatrix Lestrange nor Narcissa Malfoy to inherit all the gold the House of Black has in the vault. And so the Goblins were informed that all the gold and the properties that the Blacks had in the House of Black high-security Vault was all yours."
"Hmph, it's convenient that thanks to Mother dearest, I'm richer than I thought I was. It's nice, I guess." Sirius hummed and then furrowed his brows. "Wait, Burgock. You know that Harry is my godson, right? A contract like that is a bit unappropriate, don't you think? You know, my ancestors usually used such contract with their spouses to prevent infidelity and for extra precautions."
"Unfortunately, Mr. Black, you are currently a fugitive wanted by the British Ministry of Magic. You couldn't take the role of magical guardian. At the moment, this is your only available option," Burgock emphasised. "Do not worry, Mr. Black. The contract will be mutually beneficial. What's more, no one can dispute such contract. Not even the Hogwarts' Headmaster can interfere once Mr. Potter consented."
"Not even Dumbledore?" Sirius couldn't hide the wonder from his voice.
"As you were his legal guardian the moment his parents died to the moment you were thrown into Azkaban, I was made aware of Mr. Potter circumstances. Mr. Dumbledore is only Harry Potter's magical guardian by the lone reason that you were imprisoned. You were his rightful magical guardian still because you weren't legally incarcerated, as such, Mr. Dumbledore's role as a magical guardian to one Harry James Potter is barely legal. You know what this means, don't you, Mr. Black?"
Sirius swallowed. He looked down at his lap. "I could make him live with me."
The contract would make Sirius know whatever condition Harry was in, he could know his location, he could project his thoughts over to Harry's mind via a mind link that would form once Harry agreed to do this with him, he could also share... memories. A plus to all this, though; he didn't need Dumbledore's permission. He only had to sign the contract in Harry's stead as he was still Harry's (not really official) magical guardian.
Sirius smirked wickedly, feeling rather vindictive even if he felt rather irrational about all this. But Dumbledore had done things without seeking permission from anyone just because he could, so...
"So what do you say, Mr. Black?"
"I'll do it." Sirius inhaled and flashed the Goblin a grin.
"Excellent. Odbert there, get your arse over the Black Vault and fetch me the parchment with the word 'instructions to make the Black's specialty'."