Your footsteps echoed in measured beats, a prefect's rhythm worn familiar by countless nights. Left past the Slytherin common room entrance. Right at the tapestry of Barnabas the Barmy. Down the sloping corridor toward the Potions classroom.

That was when you heard it. A soft scrape of wood on stone. A hinge, long un oiled, groaning.

The classroom door stood open.

Not wide. Just a crack. Enough for a sliver of candlelight to bleed into the darkened hallway. Enough for the sharp, honeyed smell of amber liquid to curl toward you.