alright so i know we are all into punk sirius who is hot on slumming it in his teens, showing just how connected to the working classes and the great unwashed he is by living in a tiny poky flat in London, BUT I submit, for your delectation:

everyone lives au in which sirius decides to reverse stick it to his fam by joining forces with andromeda to become the hot new socialites in magical britain, hosting charity balls for postwar rehabilitation and like, vampire & werewolf charity fundraisers - lavish affairs in which the rich and the beautiful are subtly pressured into outbidding each other into donating more and more absurd amounts of money or else risk being socially ostracized FOREVER because they won’t receive one of those EXCLUSIVE invitations to number 12 Grimmauld Place & this INFURIATES narcissa who CLEARLY is the HEIR to the social lives of the black family and will not be USURPED by her black sheep of a sister and the family’s wild canon and dissolute disowned heir, her cousin lbr she probably bitches about this to Bellatrix’s portrait ad infinitum and Bella’s just like why don’t I have my WAND why can’t I cast spells and make her SHUT UP she and Draco grow very close in those months with Narcissa’s wailing incessantly about how NO ONE will attend any of the Malfoy’s social events and also FANCY!!!! ANDROMEDA HAVING THE AUDACITY TO DISINVITE ME FROM MY OWN ANCESTRAL HOME!!! AN INSULT NOT TO BE BORNE!!!! 

anyway, Sirius obviously throws each and every single piece of furniture in Grimmauld Place out and strips it down, knocks down a couple of walls and adds in some elegant french windows and with Fleur’s help redesigns the place entirely because for god’s sake, victorian gothic is SO last century and besides, if we’re really doing pureblood decadence the only way to go is French Rococo lbr and everything is now MIRRORS and GILT and frankly ridiculous furniture that is IMPOSSIBLE TO SIT ON but everyone adores even when they’ve been standing in six inch heels for three hours running. Walburga Black obviously has kittens over this redecoration and this meticulous stripping away of their HISTORY (we can trace our family all the way to the Norman conquest! Your great great great great great great great great great great grandfather fought alongside King William at Hastings (unlike the Malfoys who only LIE about their involvement, just so we’re clear) she shouts until Sirius reveals his party trick aka the elaborately brocaded silk curtains he’s installed to be pulled over his mother’s painting so she becomes yet another one of the #quirks of Grimmauld Place, an entertainment set piece and nothing more). 

Meanwhile in the library Sirius probably donates half the books to Hogwarts and then redoes the entire place in homage to the Brighton Pavillion (You see I’m not entirely unpatriotic, he tells the portrait of his fuming father) and then installs CARD TABLES at which the rich and the famous can do things like LOSE ENTIRE FORTUNES and also the family diamonds - all in the name of charity. 

Also, most importantly is the draw Sirius exerts on the entire wizarding world because he obviously cultivates an eccentric and bohemian persona and insists on receiving guests for one hour only from a chaise longue in one of the parlours where he reclines in these hideous brocaded silk dressing gowns, with bottles of sal vol and assorted smelling salts around him and he only ever extends a single well-manicured hand to everyone: twelve years in Azkaban, he says faintly to everyone who visits, but the healer says I should recover my nerves soon (no one knows when ‘’’’’’’’’soon’’’’’’’’’ is, but this goes on for at least ten years after the war.)

And obviously each and every single one of his relatives stuck in their portraits are clawing their eyes out or shrieking in horror about WE HAVE BEEN REDUCED!!!! REDUCED TO BEING NO MORE THAN THE LAUGHING STOCK OF BRITAIN!!! except possibly Regs who is amused at just how terribly transparent & crude his brother is at the art of provocateuring.