Character Hook: The Train Shade

There's this guy on the train. He looks older: mid 40s or early 50s. Thin. Not too tall. Snappy dresser, usually a yellow polo shirt and slacks. Shaved head under a cap. Always wears dark glasses. Always carries a brown leather soft-sided briefcase.

Is this his natural form?
By nJoo at deviantART.

He has this presence, like you can feel him come into the room. And here's the kicker: Whenever he walks, he rattles and clanks like he's wrapped in chains from crown to sole.

I'm to the point of staring as he walks by because I can't figure out what's making the noise. The bag is closed and doesn't move. Does he drape chains down the inside of his pant legs for armor? Is he really that good with special effects? Is he a Foley artist?

Or is he haunting the train?

Dear Lord. Am I the only person who can see him?