Y/n pressed their forehead to the cool glass of the compartment window, watching the Scottish countryside blur past in smears of green and grey. The compartment was empty—had been empty since King's Cross. The trolley witch had come and gone, leaving a crumpled wrapper and the faint smell of pumpkin pasties.

Somewhere down the corridor, a group of students were singing something off-key. A door slammed. Laughter. The rhythmic clack of wheels on track.

And then—quiet.

The door slid open with a soft hiss.