Our tenth and final question comes from heavensgardener, who asked...
"I'm curious about Faerie and trans* people: are there any trans* and genderqueer fae, and if there are, how would this be handled legally/socially/etc? "
This is a great question. This is an important question. And this is a question where I am going to begin my answer with a disclaimer. Namely:
The fae are not human. The reason we have a changeling (Toby) as our primary entrance into the world, with a Cait Sidhe as her main love interest, is because in many ways, the older purebloods of the Divided Courts are so inhuman that they are difficult to explain. Some of them, like the Luidaeg, have spent so much time around humans that they've started thinking like humans do, but for the most part, they are intelligent creatures who are not us. Because of this, when I answer questions about the fae, a) I sometimes need to answer for purebloods and changelings separately, and b) an answer that is about purebloods is not a statement of how I necessarily think things work for real humans, in the real world. Okay? Okay.
There are absolutely genderqueer fae. There are fae, such as the Undine, for whom a human form is a choice, and so they go with whatever they feel. Lily identified as female, so she was almost always female when she talked to Toby; there may have been others for whom she took on a male form, or a completely androgynous one. There are other fae who just don't think it's any of your damn business, and conduct themselves accordingly. The only time anyone will ask them to "commit" to a gender is when it's time to have an heir, which means that if they're not in the direct line of descent, they don't have to worry about it. There have been a few surprises when "Daav you know, Daav, doesn't like pronouns, always sort of assumed they had a penis? Yeah, well, Daav's pregnant," but on the whole, it's no big deal.
It's a bigger deal for genderqueer changelings, who exist at about the same percentage that they do in a human population (maybe slightly higher, as they are more likely to encounter positive genderqueer representation if they're growing up in the Summerlands). Changelings living in the mortal world have to deal with mortal shit. Changelings living in the Summerlands are often being raised by their fae parents, and fae parents can be weirdly gender essentialist about kids. IE, "I have wanted a daughter for three thousand years, you are going to wear that dress if it kills you." Sometimes fae parents do this with no concern for their kid's gender identity, because pureblood parents can be absolute assholes.
Trans fae are somewhat less common than genderqueer fae, and most of them, because they live in a magical world, will just go "well, I want transformation magic now," and have done. The only way to get a permanent transformation spell is to get it from one of the Firstborn, but re-casting once every hundred years can seem like a small price to pay.
Some alchemists have figured out how to make what are essentially the magical version of hormone replacements. This is because alchemists tend to prefer slow, steady, permanent solutions to "wave a wand and it's done."
Fae are very respectful of pronouns and gender declarations. The question of succession is usually handled by either naming a brother or sister's child as heir, or training an heir from a completely different bloodline, or marrying someone with whom a child is possible. (For someone using transformation spells, which would provide a complete biological reweaving, at least in the short term, this is easy. For someone using alchemy, this is harder. For someone who has made a deal with the Luidaeg, this ranges from easy to impossible.)
Trans changelings face many of the issues trans humans do, with the added options of using transformation magic or alchemy (and thus tying themselves more permanently to Faerie).
Selkie skins are interesting, because they transform the wearer from human to seal and back based on what their wearer knows themselves to be. So a Selkie who receives their skin will transform for the first time, and then return to an ideal version of themselves. This can mean a change of visible gender, and a great relief to the young Selkie.