Number 12 Grimmauld Place is not home. It is cold and harsh and loveless and it isn't home.
Hogwarts is not home. For awhile he fancies it might be, because he likes it here, because people here like him and it's an escape from that place that definitely isn't home. But in the end, Hogwarts is a wonderful place, a magical place but it isn't home.
(Close but no cigar)
The Potter home is not home. He thinks it is, thinks it is from the moment he climbs in James' window at 2:44 am having fled that place he always knew wasn't home. He is loved here, he is happy here, he belongs. It smells like apple pie and fireplaces and cologne and James' broomstick polish. He never wants to leave because this is home. Except it isn't.
(You're getting warmer though)
His flat is not home. It's a tiny thing, kind of cramped and nothing to marvel at but its his, his and James' too and he almost fools himself that it's home. He is independant here, no rules, no disappointment. He feels free and happy and reckless. It smells like broomstick polish and fresh air and wet dog and aftershave. It smells like him. It smells like James. It isn't home.
(But you'll notice the ones that almost are all have one thing in common)
No place has ever been home.
But that doesn't mean he doesn't have one.
He has a home and it moves around a lot and sometimes they share a house and sometimes not. His home smells like broomstick polish and aftershave and fresh air. His home makes him feel brave and happy and safe. His home is everything he's spent his life searching for. Home means being loved, means being safe, means never being alone.
Home is a tall boy with messy hair and glasses. Glasses he breaks at least once a week (because if he doesn't break them at least once a week, then he isn't him). A boy who always sleeps with the windows wide, wide open even in a blizzard or a monsoon (it's at times like these that sharing a house isn't exactly ideal). A boy who loves flying and winter and custard, a boy who gave Sirius everything. Home is his best friend.
Sirius Black's home is James Potter and it's as simple as that.
