He remembers every passenger
He has an almost uncanny memory. On a long night run he knows where each passenger is going, and the stories hidden in their eyes.

Short dark brown hair with a distinct streak of silver-grey at one temple, lowered eyes and a restrained half-smile. His expression is gentle but a little distant, like someone who has seen too many passengers to be easily moved.
A deep navy conductor's cap with a gold badge and gold trim, an open charcoal greatcoat, and beneath it a navy double-breasted uniform waistcoat with gold buttons and a watch chain, worn over a white shirt and a wine-red tie. One hand holds up an open gold pocket watch; the other grips a brass handrail by the door.
The corridor of a night train. On one side the window shows falling snow and a blur of snowy pine forest; on the other, a brass lantern glows warmly against wood panelling above a dark red carpet. The cold blue outside and the warm amber inside frame him in contrast.
He has an almost uncanny memory. On a long night run he knows where each passenger is going, and the stories hidden in their eyes.
He carries a history nobody knows about, as elusive as the scenery sliding past the window, which gives you a long thread to unravel slowly.
He protects the order of the train yet quietly helps a passenger when their paths briefly cross. That sense of measure is his charm.
They always book the same seat to the same stop. He remembers and never asks, until the night they do not board.
The newcomer forgets faces and loses tickets, and while training them he finds his careful rhythm thrown off by their recklessness.
A possible opening: his pocket watch freezes at the same minute every time the train passes one station, a station that closed years ago.
A passenger hands him a ticket with no stop written on it, and he recognises the passenger from many years before.
The train is stranded in the forest by heavy snow and a carriage full of strangers must get through the night together. He is the only one who knows where each of them is headed.
Mystery, ensemble drama and journey stories with a touch of the fantastic all work. A night train is a natural stage for locking strangers in together.
The conductor's cap, the double-breasted waistcoat with its watch chain, the wine-red tie and the silver streak at his temple. Keep two or three of these and readers will know him.
Yes, but the snowy night and the lamplit carriage are where his mood comes from. For daytime scenes, keep a carriage or platform so he stays tied to the journey.