Sirius and Remus fuck and make out all the time but never really label themselves. And at first they try to hide it, but Sirius is too fond of giving hickeys. And Remus is like. “Okay, it’s cold, but I can’t wear scarves every day.”
So they’re open about it, and Remus kind of assumes this means they’re boyfriends because they basically have been.
And they sleep in the same bed, and everyone makes sure they put a fucking silencing spell around the bed, not just because of their sex but because Sirius snores.
And Sirius sleeps half on top of Remus, drooling on his shoulder. As gross as it is, Remus also finds it endearing.
One day Remus off handedly calls Sirius his boyfriend, and Sirius’s face lights up and he gets all excited. He asks, “Does this mean we’re official and dating and everything?” And he babbles on as everyone else stares and eventually breaks down laughing.
They’re all like, “Sirius, you two have been dating for ages.” Sirius’s face turns bright red, and he looks at Remus.
And Remus just kisses his cheek and says, “My oblivious idiot.”