There is a particular stillness that falls over Hogwarts during an eclipse. The kind of hush that makes even the portraits stop pretending to sleep and actually watch the windows.

The moon had begun its slow, deliberate slide across the sun that afternoon. The light filtering through the castle's ancient windows turned thin and grey—silver at the edges, like the whole world had been dipped in old photographs. In the Great Hall, students whispered; the sort of whispers that had nothing to do with secrets and everything to do with the uncanny feeling that something ancient had just turned over in its sleep.

Regulus Black felt it before he saw it.

One moment, the shadow at his feet lay exactly as it should—obedient, precise, attached to him the way Black family shadows had been attached to Black family heirs for centuries. The next, it was gone.

Not gone. Moving. Sliding across the stone like spilled ink, pouring itself toward the window, lengthening, stretching, reaching for the tree line of the Forbidden Forest in a way his shadows had never once done without his command.

Something in Regulus' chest went very, very still.

The shadow did not answer. It simply continued to pull toward the forest, drawn by something beyond the wards, beyond the castle, beyond anything Regulus could name. For a boy who had mastered the Black family's shadow magic before he'd mastered his own handwriting, the sensation was... unsettling.

And so, because Regulus Black was not the sort to ignore a mystery—especially one written in his own bloodline's magic—he followed.

He moved through the castle with the quiet fluidity of someone who had spent years learning to walk without sound. Past the library, where a cluster of Ravenclaws had abandoned their books to press their faces to the windows. Past the seventh-floor corridor, where the Slytherin eighth-years had evidently decided the eclipse was an acceptable excuse to skip afternoon lessons.

The Forbidden Forest loomed before him, darker than it should have been in the middle of the day. The eclipse had stolen the light, and the forest had taken advantage. Its shadows were thick, velvet, and faintly hungry.

And that was when he heard them.

Voices. Laughter. The unmistakable drawl of Draco Malfoy, the low murmur of Theodore Nott, the sharp, bright edge of Pansy Parkinson's commentary. The Slytherin group was already out here—of course they were. Where else would the heirs to Britain's oldest houses be during a celestial event, if not standing at the edge of something forbidden, daring it to react?

Regulus might have turned back. He might have decided that whatever was pulling at his shadows could wait, that the forest would still be there tomorrow, that he had no interest in joining whatever performance Draco was undoubtedly putting on.

But then his shadows surged, and the trees parted, and the entire world went strange.

She came from the forest like a piece of midnight detaching itself from the rest.

Barefoot. Her feet made no sound on the forest floor—not because she was careful, but because the ground itself seemed to hold its breath beneath her. Starlight clung to the edges of her hair. Shadows curled around her wrists like living bracelets, and they moved with her, not against her, as though she were the place they had always been trying to reach.

The Slytherin group went silent.

Every single one of them.

Draco's hand had been mid-gesture—some theatrical point toward the sky, no doubt—and it simply stopped there, suspended in the grey air. Pansy's mouth opened, then closed again. Theodore's eyes tracked the stranger with the same unblinking focus he usually reserved for things that might kill him. Blaise's expression flickered, then stilled, his head tilting a fraction of an inch to the left.

And Regulus—standing just beyond the group, half-obscured by the shadows of the tree line—felt his own shadows reach toward her like she was gravity.

He didn't speak. Couldn't. For one horrible, wonderful, impossible second, Regulus Black—The Genius, the heir, the boy who had never once been rendered speechless by anything—forgot how words worked entirely.

The girl stepped out of the Forbidden Forest and into the clearing, shadows still woven through her fingers, and looked at the Slytherins like she had never seen a human being before.