And how it can be treated in retellings. I’m going by assumption that fae are inherently eldritch and uncomprehensible creatures, metaphysically akin to spirits or ideas, and not human at all.
Most often I see idea of human child fighting back to escape to human world, and fae child accepting and growing in human culture and thinking like human. And it’s fun but I’m thinking of something else.
Human children who come to Faerie and cannot survive. Human children who are transformed in something less than human but more than this alien creatures. Human children who are driven mad by Fae.
Human children who cannot imagine getting away from fey because everything is so much more beautiful than in human world. Human children who never quite fit in human world anymore. Human children becoming friends with halfbreeds
Human children who are treated as pets and have problems with adapting to human world where they are as much as people as anybody else, and not small, tiny things that are constantly at threat of getting shattered by Faery’s insane unreality. Human children trying to rip away magic and make themselves truly mortal. Human children using their knowledge and power and experience to warn people and bring back other children (not by killing fae, because that is something you cannot really do, but by using laws of Faery and bargaining and favors).
Human children who feel bad because they aren’t as powerful as their fae family and can never truly understand each other and are at such danger constantly. Human children who think their fae upbringing made them happier than human world (maybe they stepped out of reality on their own). Human children being loyal and willingly serving fae.
And changelings, who may be an adult fae playing role, or newborn fae hidden away at human world (because there are Rules and Laws and if you take something you have to give something up). Changelings who are no matter what, inhuman, alien creatures of magic and unreality who cannot comprehend mortal existence at all, who may learn to like humans they are living with and help them out and protect them but they are never going to choose humanity over Faery, because they aren’t men, they are something Else and their very nature prevents them from even thinking of that and when they get bored or called back will simply leave without microsecond of hesitation.
So in short, human beings warped by Faery and something else with varied views on their situations, and Fair Folk who no matter what will never understand humans or choose them over their own.