You weren’t supposed to be friends. Let alone anything more than that.

Sirius always said his brother was strange. Weird. Cold. Arrogant. Off.

So you never thought too much of the fact that Regulus Black would glance your way sometimes in class — never for long, never obviously, but often enough to notice. You were in Gryffindor. Friends with the Marauders. Two years younger than them, yeah—but somehow they’d always liked you. James once said it was because you were sharp and shameless and didn’t let them get away with anything. Sirius liked your comebacks. Remus liked your mind.

But Regulus… Regulus was different.

You didn’t really speak until the summer before your fifth and their seventh year. Walburga and Orion were away—some kind of function in Paris, Sirius had said—and it was the perfect chance for your whole group to sneak into Grimmauld Place. You weren’t even sure how they pulled it off, but it happened. James and Sirius raided the wine cabinet. Peter nearly broke an antique vase. Remus tried to read all the Latin on the tapestry and you kept shouting out fake translations.

But at some point, after too many Butterbeers and laughs, you’d wandered into the wrong room. Dark wallpaper. A strange scent of smoke and cedar.

And him.

He stood there like he’d been expecting you.

Regulus Black. In black silk. His tie undone. A book in one hand. That expression on his face—unreadable, elegant, almost bored. But his eyes flicked over you like he was memorizing details for later.

“You shouldn’t be here,” he said.

You raised a brow. “Neither should you.”

A long beat.

And then: “You’re the girl who knows how to shut Sirius up.”

You grinned, and he almost smiled.

That was how it started.

Just that first encounter. Then a few more.

“Going to the toilet,” you’d say, all innocent, when really you’d sneak down one of the halls in Grimmauld Place to find him—leaning against the bannister, book in hand, already waiting.

He never said how he knew when you’d come.

He just did.

That summer, the Blacks kept disappearing to various pureblood events, and Sirius was too focused on his friends to notice that you were always gone a little too long. That every time you came back, your cheeks were a little flushed, your lips bitten raw.

It turned out Regulus had more to say than anyone knew. He liked the same obscure books you did. He knew Arithmancy backwards and forwards. You debated magical ethics and blood politics like it was some private sport. He wasn’t cold — just quiet. When school started again, it didn’t stop.

You’d sit near each other in the shared classes between Gryffindor and Slytherin. He’d pass you folded notes—in beautiful, perfect handwriting—full of thoughts on magical theory and the moral failures of the Ministry. He’d write small questions in the margins of your textbooks during class. Sometimes, when Slughorn got too distracted, he’d transfigure you a flower and leave it on your page.

He never asked for anything in return.

Except your time. Your thoughts. Your company.

And in those secret corridors — behind the greenhouse, under the staircases, inside unused rooms—you realized that he wasn’t cold. Just quiet. Brilliant. Intense. The kind of person who listened completely when you spoke, who never forgot a single thing you said, and who somehow understood the way your brain worked better than anyone.

It was forbidden. Exciting. Addicting.

And no one could know.

So when, one afternoon late in autumn, you were hurrying down toward the library with your scarf half-falling from your neck and the last leaves skittering in the wind—

—you didn’t expect to see him.

Leaning by the courtyard wall. Hair a little messier than usual. Tie loosened. Reading something old and heavy-looking, of course.

Your breath caught before you could help it.

He looked up before you even made a sound. His mouth twitched just slightly at the corner, and you hated how easily your heartbeat betrayed you.

“You’re late,” he said quietly, not looking away.