What can I say but wow.
This story is quite well written. I could almost feel what it would be like to be on a train in the mountains of Chili. The details about our hero are given well enough that you can start to know what type of person he is, yet at the same time not feel like an info-dump.
The encounter is extremely erotic and arousing, and leaves you wanting more. It is also partly frustrating because you find out so little about the encounter and want to find out more.
There is a bit of information at the end that almost (almost, not quite) feels like an info-dump of background information. It might have been better placed or described, but that may just be my personal preference.
My only nit about the story is that there is one sentence that I missed the first time around describing an ability the man has. If you miss it, like I did, there are parts of the story that get very confusing. However, it is entirely possible that is due to my not paying attention and not the way the author wrote the story.