Faerie Changelings are just a part of Faerie lore, so I included them for a little spice. They are a part of this story because changelings (both the human and the faerie) are outcasts. This can be a strength or a weakness, as being an outcast in real life can be. Faeries choose to steal a human child away from their human family and replace that child with a faerie if the humans have somehow found a way to negatively impact the faerie realm, it's mainly a revenge thing. Once a human enters the faerie realm and specifically partakes of faerie food and drink (as a human changeling must to survive) they can never leave. The humans are stuck there, and depending on which court they are in they can be anything from a slave, a servant, or a friend. Some faeries feel sorry for their human counterpart, some feel responsibility for them, and some simply hate them for taking away their faerie childhood in the faerie realm. I hope that helps. The faeries would be expected to fight in the war alongside the court of their birth, the humans are simply stuck their in the middle.