Sirius has a flat of his own in a three floor walk-up in the north of London. His neighbours are all Muggles, all at least eight years older than him and spend most of the time at work. They'll ward the building from his family.
The flat has a separate kitchen and bathroom, and a bedroom with a window onto the light-well. It may not quite be home like Hogwarts or the Potters', but it frees him from the unreasonable expectations of his parents, and that's enough.
The first evening in his flat, Sirius has to leave to hunt down a teacup. Near the bus stop he discovers a second hand store in the shops that is like an indoor version of an odds and ends stall. There is a teacup in the dresser at the back sticky taped to another. He buys both of them.
For the first two days he's in his flat, the only food Sirius has comes out of the picnic basket Mrs Potter presented him when he left James's, just a week before spring term. His first meal consists of a pork pie and the end of the loaf of bread.
Although Sirius's food has always just come from the kitchen of whatever building he is in at the time that he is hungry, he knows that James, Remus and Peter have all managed to cook for themselves.
All Sirius has to do is find ingredients. This becomes more urgent on the third day, when the bread is going stale and the pork pies have all been eaten. It's an adventure, and Sirius has enjoyed those in the past.
The local shops include a small grocers'. Sirius doesn't quite know what to make of the rows of the same sort of food in different coloured boxes or the fact that the counter separates the proprietor from his goods. Whenever Sirius accompanied his mother on errands, she would simply demand what she wanted from an assistant who would scurry to find it. Remus and Peter tried to explain once that Muggle food shops were more like Flourish and Blotts than an apothecary or a market, but that doesn't help Sirius choose from the bewildering display of options.
He does find easily identified tea and milk, for which he is thankful. And also tuna, because he remembers that he both likes sandwiches and knows how to make them. The cans are clearly labelled; he buys four. He thinks he probably can't get very sick of fish in just a week.
The first time Sirius really loves his flat is the second morning, after eating Mrs Potter's plum jam on bread for breakfast accompanied by tea, when he leaves the mugs in the sink without washing them and takes a shower at exactly the time he wants to. He sings loudly while he masturbates, and no one shouts at him through the door.
The feeling of euphoria lasts forty seven minutes.
In the evenings there is nothing to do except his Arithmancy and Transfiguration homework. Writing supremely clever insults on bits of parchment and sending them flying around the room is much less fun when there is no chance of them hitting Regulus in the ear.
He doesn't waste any time thinking about the fire in his parents' library or getting Regulus to sneak into the kitchen to beg food from Kreature.
It is absolutely brilliant having a bedroom to himself, without snoring roommates or prying house elves. There is nothing to delay his tumble into sleep. Though he wakes every time a dog barks or an emergency ambulance nee-naws down the major road. He never had such trouble sleeping in the forest on full moon nights, despite all the wild noises.
It is fit for neither man nor beast outside, something Sirius knows from personal experiment. There is horrible, driving sleet and occasionally real snow. If he weren't a wizard he would probably freeze in his flat, but he is a wizard, so it's perfectly adequate.
Sirius isn't allowed to Apparate yet. It takes him fifteen minutes to realise that he walked the wrong direction from the bus stop, and a further ten to work out the correct direction to make it back.
He worries that this might be a metaphor for his situation.
When Sirius finally gets around to the washing up —two teacups, a fork, one and a half plates, three bowls and two spoons—he stacks everything neatly in the right hand cupboard on the left side of the sink, above the cupboard with the food in it.
They sell take away pizza from the shop opposite the grocers'. Sirius only has to go in, tell them what he wants, hand over some of the money he got from Peter for his birthday, and he has both tonight's dinner and tomorrow's breakfast. It's the sort of shopping he understands.
The pizza is kind of chewy and he's not quite sure what it actually has on it, but it's hot.
Sirius discovers curry his third afternoon, just before sunset, when there was a brief break in the weather and he ventures out in search of food which wasn't cold canned tuna or stale bread.
Curry is the most awesome invention ever. It is Sirius's new most favourite dish and definitely a mark in favour of his flat, which now smells more like curry than wet dog.
It turns out that cheese on toast, a dish that should be straightforward to concoct, isn't. Also, the smell of burnt cheese is almost as nastily pervasive at the smell of wet fur. Sirius eats the last of the bread with a scandalous amount of the jam, which is, after all, delicious.
If Sirius's parents visited, or attempted to take him back home, or even came to give him the things he left behind at home last summer, he would close the door in their face in a mature manner to proclaim his self sufficiency.
He has practised his expression of scorn in the bathroom mirror. Neither Regulus nor James is there to tease him for making faces at himself.
It's late morning, and James isn't there to think up cool and probably illegal uses for the Arithmancy work Sirius has been assigned, when Sirius absently opens one of his empty cupboards. He stares at the bare insides for several moments.
He moves one of the teacups there. It's a spare cup, anyway, just in case he ends up with visitors.
Remus arrives while Sirius is in the middle of searching his flat for soup, or soup ingredients, or the inspiration to turn curry, the last can of tuna and the remainder of the cheese into soup (probably also using the milk, but not the jam).
Remus mocks Sirius's flat, the fact that Sirius ate curry for breakfast, the fact that the Potters feed him better than he can feed himself, and the fact that his teacups live in different cupboards.
Sirius doesn't complain that the flat is too quiet or tell Moony that he misses him or confess that he feels cold despite the heating charms. But he does admit to wanting soup. Remus knows about soup, but he withholds his expertise until Sirius has plied him with tea. Smug bastard.
By the time Sirius defends himself to Remus, makes a pot of tea, and drinks his cup, he feels ready enough to brave the grocers' again. Remus leads him through the aisles, picking boxes and cans and vegetables with familiar and envious ease. Sirius watches him with not quite familiar awareness. He has never really had time to watch Remus before, and it occurs to him to wonder why he never made some.
The first time Sirius kisses Remus is immediately after Remus kisses Sirius, just inside Sirius's flat, with bags of groceries at their feet and snow melting in their hair. It makes everything deliciously warm.
The bed that came in Sirius's flat is almost too small for two people to share. They manage by tangling themselves together: Sirius's leg over Remus's and Remus's arm under Sirius's neck. Remus isn't even smiling, he's just watching Sirius through half open eyes and breathing slowly, but Remus looks more relaxed than Sirius can ever remember him being.
It makes Sirius feel proud and grateful to the whole world, to be able to have this.
Sirius has a flat of his own. He has enough teacups to have a visitor, he has all the ingredients he needs to make soup, and Remus looks content, lying naked in Sirius's bed. That's all he needs to call it home.