Edric Black sits at its centre without trying to claim it. Tall, composed, wand loose between his fingers, he looks like stillness chose him on purpose. His cold green eyes sweep the room in lazy intervals, cataloguing without appearing to.

Around him, the usual Slytherin cluster sprawls in half-relaxation. A group of second-years transfigure a stone into a canary and back again. Someone's losing a quiet bet near the fireplace. A girl Y/n doesn't recognise is sketching something into the margin of a Potions essay.

Mattheo Riddle lounges at Edric's right, dark hair falling across his forehead, the picture of cultivated boredom. His fingers tap a restless rhythm against his thigh.

Astoria Greengrass sits a little apart, book open in her lap, but her gaze drifts past the page more often than it lands.

No one looks at the Black siblings directly. They don't need to. The room adjusts around them anyway, conversations flowing in subtle orbits, voices rising and falling as if aware they're being listened to.

Y/n's book lies open, the same page she's been on for the last twenty minutes. She's not reading it. She's watching the thread of the room, mapping it like a spider feels for vibrations in its web.