The same scarlet steam engine. The same worn leather seats. The same soot-stained windows looking out onto the same Scottish countryside.

Except nothing was the same.

Hermione had looked almost green when she'd explained it — something about the calculations being slightly off, about temporal coefficients and overlapping ley lines, about how they'd ended up forty years too early instead of a few hours too late.

And now here you were. Seventeen years old. A Slytherin prefect in theory. In the middle of a train compartment that smelled faintly of smoke and cheap perfume, with three people you'd never met before staring at you.