I've recently changed my preferred carriage. Now that there are regularly 4 carriages, I can avoid the Office Workers from Hell. Either Hard Stare Man has done the same thing, or he's following me.
There are very few other regular commuters with whom I haven't exchanged pleasantries or little wry comments over the years, or even just a little nod. Fragrant Nescafé Guy never speaks other than to exchange a gruff ETA with his wife/mother on the phone, but even he gives me a nod of recognition occasionally. Not Hard Stare Man though. He never does anything but stare.
When I catch him staring, he never looks sheepish or smiles. I don't think he's flirting. He looks more like the guy you wouldn't want to meet out jogging on your own. Every time I catch him looking at me, I hear the "donk donk" from an episode of Law & Order.