You didn’t stop running until your lungs burned.

The castle blurred—stone walls, shifting portraits, candlelight flickering in and out of focus as you tore through the corridors, past startled first-years and the occasional suit of armor. You weren’t sure where you were going. You just knew you couldn’t still be standing in that bloody common room, couldn’t still be looking at him.

Sirius Black. Your boyfriend. Well—your ex. Effective immediately.

You’d known what you were signing up for with him. Everyone did. Sirius was a hurricane in leather boots—charming, cocky, with that infuriating way of making you feel like you were the only person in the room… until you weren’t. You’d laughed off the way he flirted with strangers, brushed aside the whispered warnings from people who claimed to have “seen him” with so-and-so. You’d convinced yourself he just liked attention. That it was harmless.

But walking into the common room tonight, grinning and ready to celebrate the Gryffindor win, only to see him pressed against your best friend, his hands in her hair, his mouth on hers—

That wasn’t harmless. That was the end.

Your eyes stung as you rounded another corner, skirts swishing around your legs. You were halfway to the girls’ dorm when you slammed into something solid.

Someone solid.

You stumbled back, ready to snap, but froze when you saw who it was.

Regulus Black.

You weren’t friends. Not exactly enemies either. Just… classmates. Same year, same classes, same circles in the Slytherin common room—because yes, you were a Slytherin dating a Gryffindor, something Sirius had always found “hilarious” and “tragic” in equal measure. But Regulus? He was a constant quiet presence. Polished. Sharp. The kind of person who spoke rarely but always noticed things.

Right now, he was noticing you.

“Watch it—” he started, but then his eyes narrowed. His voice shifted. “You’re crying.”

“I’m not,” you said automatically, swiping at your cheek. (You absolutely were.)

Regulus tilted his head, studying you like a puzzle. “What happened?”

“Nothing,” you muttered, trying to sidestep him. He moved just enough to block you again. Not in a threatening way. Just… deliberate. Like he wasn’t going to let you pass until he got what he wanted.

“It’s my brother, isn’t it?”

You froze.