Read this book on deployment that a friend was sent and I rather enjoyed it. I'm like 80% certain that the title was Iceworld, yet I get hits that aren't it. It isn't written by Hal Clement (which is the majority leader), and I'm pretty sure this was small production.
The world, which is gripped in a winter-like season that seems to happen once over a period of time (like a hundred years), is the host to the Fey. It starts off in a prison, in which the main character watches a female fey get into a fight with another fey, in which she kills him. Killing someone in a duel lets you get a braid in their hair as a mark of success and recognition (she had three, I think). The main character was once a soldier and an officer for his nations' army, but was duped and betrayed by a fellow officer and the main character's wife (in which the two got married, identified much later in the story). Somehow, humans (from Earth) can come to this world through barely explained portals/gates, and have our current technology (there are hillbillies with a Chevy Nova or Camero, shotguns, and cages made of iron). The Fey use silvered swords, as iron is poisonous to them. The main character, along with a human man and one other, are released from prison by the ruler of his nation (A Queen that may or may not be a deity or demigod/dess) to simply get some sort of amulet (or a young Fey girl). The Queen has an evil sister who rules another nation who wishes to prevent this from happening, as it is the source of her longevity (the Queen's been around for at least 500 years). There is an example of time travel, humans having Fey children, inter-dimensional travel, quite a few duels, a event of flying (possibly in a ship or contraption), driving in a car that had to be covered with blankets for the Fey members, and a Queen that can possibly live forever by transfering herself into a body of a particular girl. She may have even been refered to as the Spider Queen.
This is none of the usual suspects; not Forgotten Realms, or any book associated to an RPG. I think this was from a smaller publishing company, and as I said, I'm only 80% sure the title was Iceworld, but haven't gotten a hit. Of course I don't remember the author, any of the characters' names, or anything else that would make this easy.