The usual group had claimed their usual corner. The worn leather sofas, the low table littered with half-empty butterbeer bottles and a scattered deck of Exploding Snap cards.

And Mattheo was in his usual spot. The corner of the largest sofa, one leg thrown over the armrest, head tilted back, a faint smirk playing on his lips as he listened to the banter.

It was familiar. Comfortable. The same faces. The same voices. The same rhythm that had played out a hundred times before.

Then the door to the common room opened.

The cold air from the corridor slipped in, carrying the faint crackle of torches and the distant echo of footsteps. Conversations didn't stop. Not right away.

But a few heads turned.

Standing in the doorway was a girl Y/N had never seen before. Dark hair, sleek and straight, falling past her shoulders. Sharp features, high cheekbones, eyes the colour of winter frost.

She wore Slytherin colours, but the cut of her robes was unfamiliar. Slightly different. Foreign.

She scanned the room once, unhurried. Then her gaze landed on the group by the fire.

She laughed at Draco's dry comment. Quipped back at Theo. Charmed Astoria into showing her the trick with the cauldron cakes.

And when Mattheo finally spoke—some low, lazy remark about the dungeons being better than wherever she'd transferred from—Seraphina turned to him fully.

Y/N sat on the edge of the sofa, her half-finished drink in her hand.

Nobody had introduced her yet.