Chapter Text
The first thing anyone learns about Regulus Black — aside from the fact she looks like she walked out of a fairy tale with her dark waves and sharp silver eyes — is that her brother, Sirius Black, worships the ground she walks on .
From the moment she steps onto the Hogwarts Express for her first year, Sirius makes it everyone's business to know:
“ That’s my baby sister. Look at her wrong, and you’ll regret it. ”
James laughs, nudging Sirius. "Mate, you don’t need to scare the entire train."
" I do. Have you seen her? She’s too soft for this place. "
But soft isn’t quite right — Regulus is quiet, sharp as glass, poised like a queen, but small, and Sirius can’t help but think everyone will try to break her.
When the Sorting Hat calls "Slytherin!" across the hall, Sirius's face falls for a split second , but when Regulus meets his eyes from across the room, looking nervous and searching for him, he winks and smiles big enough to split his face .
“Still my sister,” he mutters to himself.
—
By third year, it's a running joke that if you want to live, you don’t mess with Regulus Black.
Even Barty Crouch Jr. — charming, flirty, smug Barty — gets a look when Sirius sees him lean a little too close.
" Oi, Junior. Find someone else to annoy, yeah? " Sirius growls, throwing an arm over Regulus' shoulder like a shield.
Regulus rolls her eyes, but she always lets Sirius guide her away .
“You know, I can handle myself.”
“Yeah, well. You shouldn’t have to.”
—
If she’s sick, Sirius is there — sneaking out of Gryffindor tower, arms full of stolen chocolate and tea.
If she’s sad? Sirius is storming through the castle looking for whoever dared upset her , James and Remus trailing behind trying to calm him down.
“Who was it?”
“Sirius—”
“No, Reg, tell me who.”
“It’s fine—”
“
Nothing
is fine if you’re crying.”
—
When she gets asked to the Yule Ball in her fourth year, Sirius almost explodes.
“Who? Who is he? How dare he?!”
James, from behind him, snorts. "She is allowed to have a life, mate."
"Not until she’s thirty."
But when he sees her in her dress that night — elegant and glowing — he can’t help but smile, even as he threatens her date .
"You bring her back safe and happy, or I swear—"
"Sirius!" Regulus hisses, tugging on his sleeve, face pink.
Still, he walks away only when she promises she’ll be fine .
—
Through every year, through every struggle — Sirius is there.
A hand on her shoulder, a shield in front of her, an arm around her waist when she looks like she’ll break.
Because to Sirius Black, Regulus isn’t just his little sister. She’s the one person who’s always been there, the person he’d burn the world for.
“I don’t care what house you’re in, Reg. You’re mine before you’re anything else.”
"You’re ridiculous."
"Yeah, well. You love me for it."
"...Maybe."
And Sirius grins because he knows — she absolutely does .