In the books, it is stated that Harry needed to stay with his blood relatives in order for the protection from Lily to work. Fair enough. That doesn’t excuse the lack of supervision for the Dursleys in the years he was there, but picture this alternative:
Sirius Black doesn’t go chasing after Peter Pettigrew and getting himself stuck in Azkaban for 12 years. Instead, he snaps back into focus and realizes his number one priority is Harry.
He and Dumbledore get into a fight and Dumbledore is forced to explain his theory and why Harry will be the safest with Petunia. If it’s for Harry’s sake, than maybe this old geezer has a point. That doesn’t mean Sirius will go down without a fight.
The following morning, Dursleys have a terrible awakening. It’s not just Harry. Sirius Black, with a suitcase and a bike he parked in the driveway, is in their living room.
drinking a cup of tea no one offered him.
If Harry is staying, Sirius will not leave his godson alone with these muggles. He is moving to the Privet drive. The Dursleys have to agree. After all, this strange, shaggy looking obviously crazy person has magic and it’s not like they can call the police. Also, he is willing to pay them a lot more than one room is worth.
And so the sitcom about a young adult wizard, two toddlers and a pair of muggles all living in one house begins.
In the end, it’s not all that bad. Harry has the love and care he deserves. Petunia and Sirius become white suburban moms™ together as they cheer their kids on in football games and host birthday parties for their friends. Sirius’s gluten free, vegan, organic chia seed pudding are way better than the one that stupid Karen from across the street makes and that makes him a great ally. The moments Sirius gets the hang of the dish washing charm, Petunia is on his side.
They talk about Lily and James a lot, so Harry wouldn’t forget them. Sirius doesn’t spoil him. He’s inexperienced, but not an idiot. Nor does he take him to the wizarding world a lot. After all, a kid his age doesn’t need all that exposure. Remus comes to visit a lot and they teach Harry about their world, the wonder and the magic, about Hogwarts and the Marauders. Others come by too, from time to time. More as the time progresses and Sirius wants Harry to get accustomed to their world.
Dudley can’t be a bully like his dad would like him to be anymore, nor does he want to. He isn’t scared of magic, but fascinated by it. Petunia still spoils him as much as she can, just to make sure what happened to her when Lily got her letter doesn’t happen to him. He’s a good kid, in the end.
Vernon is never 100% ok with this arrangement, even after years, but he does warm up to Sirius. They are pretty different, but that doesn’t mean they can’t at least function together. Sirius charms his car so he can avoid traffic jams. After that, they are cool. Even if Vernon still thinks they are all a bit strange.
Harry goes to Hogwart at the age of 11 and they all see him off at the station. Petunia cries, Sirius cries and even Dudley sheds a tear or two for his cousin. They are a family, after all, and Harry is loved.
So, so loved.
I WISH this had happened!