Fays are a class of immortal shapeshifters. They are not a species or race; their shapeshifting lets them move from one species to another freely.
For a start, fays are unaging, not subject to disease, and very hard to poison. Given time, they will completely heal from any wounding. Beyond that, they can be physically slain, but they don't stay that way. They come back, eventually, one way or another.
Suppose one is run through the heart in battle. It will die, to all appearances. It will not, however, rot. Left alone or in a grave, it will recover in a matter of a few days to a few centuries, depending on the wounds and the vigor of the individual, and get up, and walk away. (Very likely with a grudge. To keep hostilities from dragging out forever, fays yaoguai may commence action with mutual oaths to drop the issue after they are slain.)
But suppose a more determined enemy tosses a slain-at-the-moment fay into a volcano, or a star, or a black hole? Well, there are always physical consequences. There will be smoke from the volcano or plasma blown back in the stellar wind or a blast of radiation from the black hole. And eventually the smoke will pull itself into a cloud, or the plasma or radiation will irradiate a patch of gas that will start to condense. It may take a long time, but eventually the fay will re-embody.
"Immortal" means immortal.
By themselves, fays had only limited shapeshifting powers, centering on variations of their native form:
But then the jinn came along and taught the fay great advances in shapeshifting. Specifically, they taught fays how to copy the forms of other species. The animal Oversouls and their yaoguai agents do not let fays copy their species exactly, but there are ways around this:
Once a form is in circulation, fays can learn shapes from each other. This can be done freely, by trade, or by coercion, in all the variations of any other financial transaction. Canonically, it's trading:
Badger: "Teach me fox shape and I'll teach you badger shape."
Fox: "I'm not very interested in learning badger."
Badger: "I can also teach you raven. That's a really good shape, so I'd want another shape or two besides fox from you."
Badger: "Everyone knows mouse."
Fox: "Wren and bluebird. Bluebirds are pretty..."
Badger: "Okay, badger and raven for fox, wren, and bluebird. Deal?"
Hominids were already around when the jinn taught fays general shapeshifting, and there was a tremendous rush for fays of all sorts to learn hominid shapes.
We are used to hearing how puny and feeble humans are compared with animals, but, in fact, hominids have many desirable features, even laying aside reason and speech (which the early hominids of course did not have):
They are bigger and stronger than most other vertebrates.
They are very, very tough, being cursorial hunters.
They can eat almost anything, like a dog or a bear.
Their vision is tops among mammals, except for the poor dark-sight.
Being bipedal makes them fiendishly agile, with moves like side-steps and heel pivots.
And there are those hands.
So the great majority of fays include hominid in their repertoire of shapes, whether they started as hominid or not.
In fact, many fay tribes and nations are entirely humanoid and few members bother to learn shapeshifting.
Whatever form they take, fays always retain a default form, a "true form," to which they can revert easily. But the "true form" can change and is not necessarily the original form. If a fay practices and uses a shape often enough, and likes it well enough, that shape becomes their base or default or "true shape," and they have switched species.
Faerie is the collective name for all the enclaves and outposts held by fays. The great bulk of these are off Earth, extra-dimensional. Faerie could be defined as the fay-dominated sector of the Sundered world.
It is much commoner for fay groups to migrate to Faerie than from it. Fay connections between our world and Faerie are only possible under specific and not very common conditions.
Fays are a form of eternal life, but they are a form of afterlife. They do not normally breed; they are sterile among themselves, but can breed with other beings. Thus fays take human lovers and spouses, and nymphs often bear children to gods.
There are many theories about the origins of the fays:
The fays themselves are uncertain about all this. (Think about the many tales and controversies about human origins.) The ancient, primordial fays who might have lived through the answers are not available any longer; fays may not die, but they do pass on, bodily leaving for other realms, generally unknown to others, generally not returning.
The truth, not widely known, is a mixture of all of these. There are three broad classes of fays:
Jinn, transformations (merfolk, centaurs, satyrs, sphinxes, scorpion folk), yaoguai, thalatoi, sirrushim, and Cainites are not fays.
Part of the truth behind the idea of fays as ghosts is that common fays are not dead, but they have died. They are the appointed afterlives of animal souls that are almost, but not quite, as spiritually advanced as humans.
Common fays are the souls of animals that are fit to take the imago dei but have not yet been given it. That means that they do not have full syntactic language, do not have fully conceptual abstract thought, and are not really morally responsible. They are still definitely souls with personalities. If they do not know truth, beauty, and virtue abstractly, they do have opinions, know pleasure and pain, and love and hate and empathize and trick. If they have no real language, they still have a wide and culturally-transmitted vocabulary of utterances, expressing feelings, desires, and intentions, naming things and issuing orders. A human could be well-acquainted with such a fay, or think they were, and believe they were merely up against a high linguistic and cultural barrier.
These animal souls largely come from extinct species of hominids and from species of magical primates. It turns out that the primate order is prone to developing species with magical talent, and there is nothing like magical talent for putting a premium on evolving intelligence: you get so much more out of magic if you use it intelligently. The result is that many fays trace back to magical lemurs, pottos, and bushbabies.
In their proper afterlife, these animal souls are not merely incarnate, they are irrevocably and essentially embodied, a third thing that is not a soul in a body but soul and body simultaneously. These are resurrection bodies, after all. This unbreakable link between soul and body is why they are immortal, why they are natural shapeshifters, and why they have the capacity for magic.
These fays can be given "Adam's Mark" and thereby attain full language and reason, in ways detailed below. This makes them much more human—or as human as you can expect immortal, magic-using shapeshifters with a non-human background to be.
Common fays can become true rational souls by taking Adam's Mark. This is the imago dei, the tzelem, the specifically Adamite likeness to God that we have. It can be communicated to a fay, and it gives them that final boost to full conceptual thought and syntactic ability. They become markedly more eloquent, intelligent, insight, and creative.
Common fays can see this and so desire Adam's Mark even without understanding our state from within. And if you knew of a race of psychic geniuses, and heard you could have what they do, wouldn't you want it?
Unfortunately, they cannot realize beforehand that they also acquire our understanding of good and evil.
Even if unMarked common fays do not want the Mark, their masters may want it for them.
A Marked fay cannot take a second Mark, but can "hold" one and pass it on to another fay.
Adhene and sidhe (q.v.) cannot take the Mark and do not need it, having the same abilities from their roots in angelic nature. However, that different origin gives an alien cast to their abstractive and creative abilities.
There is no unMarking this side of Doomsday, and for anyone, fay or mortal, to lose their Mark is to be damned.
There are many ways of getting Adam's Mark. See many of the following topics.
Long before Homo sapiens appeared, much less Adamites, hominids began making tools much better and faster than any other animals, and using fire as well. In due course, some of these became Common Fays, and some Lord or Lady, adhene or sidhe (the memory is lost) devised a way of life and a shape for them to make the best of fire and tools: strong and tough to overpower and withstand rocks and fire, and if that came at the expense of size and fast long legs, it didn't matter. To make the most of the strength, they were all male; it's not like they could breed with each other anyway.
It was natural that this tribe of proto-dwarves would focus on earth-magic, the better for stone-working and later metal-working. This became part of the form, as much as the short stature, and is the basis for the idea that they are carved from earth or spring from the body of a primal earth-giant.
The first tribe grew and split and became many, so that now various races of dwarves are found in Europe, Australia, and the Americas.
Long before the jinn introduced shapeshifting to the fays, the adhene (pronounced "ad-HEEN") put their own oar in. The adhene are the angels that did not take sides in the War in Heaven. Many of them took fay form—forced into it, ordered into it by God, tricked into it, or because they wanted to: it varies from case to case. These are not adhene who merely took the appearance of animals; they became fays, with the same eternally incarnate bodies and the same range of powers, and their condition is just as everlasting as that of natural Common Fays. They differed from Common Fays in that:
They remember being angels.
They have a full, possibly superhuman, grasp of abstract and conceptual thought. If they don't use language, it's because they're past it. They can train native fay much closer to full language.
They begin with diminished powers, but they can start to work regaining them, or some of them, to a degree.
Adhene are infertile among themselves but weakly fertile with common fays. The children were never angels, of course, but exhibit the same mental and magical levels, and are reckoned adhene. Their children with mortals are reckoned high-powered common fays. Adhene and their children cannot take and do not need Adam's Mark, though they can pass a Mark along.
Under their education, common fays learned a lot of magic and got their communications abilities tuned up as far as possible. These adhene ranks as Fay Lords, but still only fays. And yet they used to be angels. Time to learn either humility or resentment.
Angels, demons, or adhene that are not incarnate may still manifest enough to breed. When they bred with humans, the result was the nephilim, demigods. When they bred with fays, the result was the sidhe ("SHEE-ah"). These are very powerful fays, fully capable of speech and rational, ethical thought, but not Adam-marked.
Like adhene, they are infertile among themselves but weakly fertile with common fays; their children are also sidhe. Their children with mortals are reckoned high-powered common fays. Sidhe and their children cannot take and do not need Adam's Mark, though they can pass a Mark along.
Prominent cultures of sidhe include the Tuatha de Danaan, the Ljósálfar and Dökkálfar, the Normebegans, and the Eldar (q.v.).
Eldar are a small but influential group of sidhe. They are to fays what Jews are to humans. Before the Flood, the deputies of the Oyeresu, i.e. the Valar, contacted a clan of sidhe living by a lake (Cuiviénen). They instructed these sidhe in the basics of monotheism and offered to lead them off Earth to a "promised land"—might as well call it "Eldamar."
Some of them, or their children (since Eldar can apparently breed, though slowly), came back to Middle Earth after the Flood with markedly advanced magic and technology, and waged wars involving potent magical jewelry. Then, more slowly, this returning diaspora left again.
They left behind powerful cultural influences among the lesser fays: languages and legends. Some fays claim Eldar blood, too. In short, Quenya and Sindarin are still spoken among fays, and Tolkien's Legendarium is his translation (and interpretation) of the Red Book of Westmarch, which records legends of later fays about the Eldar.
Fay Lords can turn mortals into fays (give them the "Fairy Mark"), and they do it by joining the mortals to a troop. Sometimes, they simply have you live with the troop for a year or so, and it just happens. But if you make a deliberate connection—eat and drink with them, dance with them, lay with them—that gives them the opening to add you to the troop at once and you are a fay. There is no going back.
Both living and dead mortals can become fays. Living recruits include:
Those babies swapped for changelings and never recovered.
Those who are captured by fairy troops and not recovered.
Those who stray into fay territory and are captured there.
Those who spend what feels like a short time with the fays, but return to find centuries have passed.
You'd think people would be lining up to be live recruits. But being recruited means being put in a troop. There are two ways this happens.
One is to win the favor of a fay Lord or Lady, who loves you enought to whisk you away for a Happy Everafter and, at some point, form a two-party little troop with you as a means to that end. There is the slightly less personal version where you are brought into a fay court and given the Fairy Mark; this is actually commoner. But in either case, it's a very personal and intimate relationship with one or a few high fays. It happens, but not often.
The other way is to be press-ganged into a troop as a minion, a Faithful Member of the Chorus. This is much the commoner troop experience, and it means forced transformation, both physical and mental, and loss of freedom, lucidity, identity, and individuality. And it could last for centuries. Or millennia. It happens, but people don't line up for it.
Dead recruits include:
Trimmers rejected by both Heaven and Hell, who are therefore available to the fays.
Folk who, while alive, made a bargain with the fays to join them.
Those who spend what feels like a short time with the fays, but return to find centuries have passed and that they have died in the interim. These are the ones who vanish when they understand the time-slip.
The problem with recruiting the dead is that Heaven or Hell may put in a prior claim. So may a pagan elysium, though those are easier to fend off. That leaves Trimmers, mostly. But people who certainly don't seem like Trimmers do get recruited. One theory for this is that Heaven and Hell are not nearly as thorough as is generally believed. Another is that fayhood is this person's assigned purgation. Another is that these new fays are (generally unwitting) deep-insertion agents for one or another Higher Power.
Because most fays are poor at speech and abstraction, or were for a very long time, there are no overarching organizations in fay society. In Europe, it looks superficially feudal, because it is a tissue of personal loyalties, but there is no equivalent to bodies of law or an enforcement of principles by a church or nation states, nothing that could organize large populations of fays.
Fay society is only a mass of small bands, seldom over a hundred, usually much smaller. They are similar to one another due to common descent and long association, but they do not form more cohesive wholes like nations. Each band interacts with a few neighbors and that's it.
Fay royalty and high lords form a wider-spanning network over these smaller groups, but they have not been able to impose organization on their ... property.
There are two kinds of fay societies: courts and troops. Courts have a structure humans would recognize: a leader or a lead couple, Lord or Lady or both, and their followers, all individual personalities.
Troops are something like hive minds; the members share a common pool of leaven, always have the same level of consciousness and excitement, tend to catch moods and skills from each other, and can feel where each other are. Unless they are under some kind of management, they merely alternate between long periods of rest and bursts of dancing, capering, and charging about. They rely on their immortal endurance to do without most thing. However, most troops are under the rule of some Lord or Lady, or were at some time, and have learned to approximate normal self-sufficient behavior.
A court may also be a troop, but usually only briefly, as for a revel or a Wild Hunt.
A Fay Lord or Lady is, de facto, anyone able to form and lead a court or troop. The Angelblooded are almost always able to be Lords and Ladies, if they are interested. Certainly many Mortalborn have reached that rank, as can Marked Common Fays. It is very rare for unMarked Common Fays to be considered Lords or Ladies.
The hierarchy of status and intrinsic power runs:
Fays are found everywhere, but Europe and western Asia are their strongholds.
Norembegans and puckwudgies are North American fays. Memegwesi are North American dwarves.
Nawao and menehune are Oceanian fays.
Common Fays are animal spirits uplifted to near-sapience by (broadly speaking) natural processes. At no point, necessarily, did anyone brief them. They recall their lives as animals, though that is not a patch on what's happened to them since. They may remember family bonds, either from their mortal days or adoptive relations since, and that's all they usually know about the origins of things. They don't think about "Where did the world come from?" or any such matter, until such time as they get Marked and hear about the issue from humans. Then, of course, they hear whatever the humans think.
Mortalborn fays enter their new lives with whatever information, accurate or not, they had in their old lives.
You might think Angelblooded fays would have more inside information, and they do, but their celestial connections are not angels in grace or are even demons, and various unreliable and conflicting "family stories" have been passed down to them. The actual, primordial ancestors—original ex-angels or actual children of celestial spirits—generally haven't been around for millennia.
So there is no firm consensus of fairy history to be had from the fays.
Their knowledge of local natural and supernatural matters, though, is generally superhuman. A great deal of human thematic magic came through fays.
Fays and mortals have an indissoluble bond: they are (or can be) the same species. But mortals feel uneasy about fays, at best, because they are magic-working immortals of uncertain temper and outlook. And fays feel uneasy about mortals because they are hooked to the incalculable.
Nevertheless, there are things fays want from mortals, mainly recruits, Adam's Mark (q.v.), and leaven.
Humans who become fays have received the "Fairy Mark," counterpoint to Adam's Mark. Invented by the adhene as a way around fay-with-fay sterility, the Fairy Mark is a pallium that permanently turns the Marked mortal into a fay, an immortal soul/body fusion, with the same magical powers. This lets fays increase in number by recruiting humans.
You get the Fairy Mark by being joined to a troop (q.v.). The troop may be a simple rioting mob of fays, a migrating dance, a Wild Hunt, or a fancy and possibly more decorous set of guests in a fairy court. It can even consist of you and your fairy lover. The troop may also be of brief duration.
Do fays get in trouble with Heaven for diverting humans from their proper destiny? Hard to say. Common fays without Adam's Mark almost certainly do not, because they do not really understand what they are doing.
There are two great opposed alliances of fay courts, the Seelie and the Unseelie. The Seelie Court seeks to make its fays as human as possible; they collect Adam's Mark in as many ways as possible and recruit mortals heavily.
The Unseelie regard Adam's Mark with suspicion and hostility, and only recruit Trimmers, who have lost Adam's Mark, into their own number. They take other humans, but do not recruit and fay-mark them, keeping them as servants for their uniquely human powers. This means the Unseelie are run by adhene and sidhe, and occasional high-level Trimmers (q.v.), since these are the only Unseelie fays that can think strategically without a Mark.
Fays not aligned with either are "Wild Court" fays, though many are really solitaries, not part of any court.
(Calling these groups "courts" is a human labelling, based on a misunderstanding, picturing fays as more unified than they are. Really, the opposed courts are more like opposed bodies of opinion among the respective fay lords.)
The Seelie Court claims to be friendly toward, allied with, humanity. But obviously, enthusiastically collecting humans doesn't necessarily mean being nicer. Burger chains "love" cattle. Contrariwise, the Unseelie may not want to enlist humans, but that doesn't mean they seek to exterminate us.
Both courts can be friends and patrons, though the Unseelie do this more rarely and are touchier.
The Irish Finvarra is high king of the Seelie. The German Erlking is high king of the Unseelie. The Dagda, Goldemar, Mab, and Huon are prominent among the Wild Courts.
In practice, it may be hard to tell if a fay or fairy court is Seelie, Unseelie, or Wild. There are some trends, noted below.
There are no races of trooping fays or dancing fays. They are "just" fay psychological conditions, common to their multiple species. All the fays in a troop form a single spiritual entity by virtue of sharing a common pool of leaven. The members are not quite individuals, but like coral polyps that are part of a single reef.
Troops may be independent, include a Fay Lord as a member, or be owned by a Fay Lord.
Troops are adaptive because they can coordinate with preternatural efficiency and can briefly focus the prana from their pooled leaven to do major deeds. It is trooping fays that fly from England to France in a breath, or go storming across the sky in Wild Hunts (see below).
It is troops that take adult humans as captives in fairyland, not individuate fays. Once the captive is past reclamation (they have eaten fairy food, or too much time has passed; the criteria vary from one troop to another), they are Fairy-Marked, no longer spiritually human, and are in the troop permanently because their leaven has been pooled with the troop's.
To leave a troop after acquisition is an in-Faerie adventure; we have no instances in our folklore. The escapee must learn to steal leaven and then successfully run away, or get exiled, or get big help.
Troops have a natural tendency to want to enlarge as much as possible. This is dangerous. The larger they get, the more often and more intensely they will fly off into a frenzy. Mild instances are just nights of revelry or trooping that is merely merry. In worse instances, they engage in actual trooping, rushing in rioting processions across the countryside, often harassing or capturing humans or other folk.
Because large troops become intractable, Fay Lords don't want troops to get too big, even if they are owners and sometime members. Even if—or especially if—they are another Lord's troop: a constant cause of battles among fays. Even an independent, lordless troop will get culled from time to time, by a neighboring troop or Lord.
A cull is an opportunity for a captive to leave. Of course, it's now been centuries; you've been one of these creatures longer than you were human.
Troops acquiring humans get Adam's Mark if they didn't have it; they lose it if all Marked members leave (so you can unMark a troop by culling out all the Marked members). UnMarked trooping fays don't usually have a lot of individuality, but some do have a lot and many have a little; Marked troops certainly have individuals. If frictions get too high, people can wind up exiled—another way of getting out of a troop.
Since Adam-Marked troops are more fractious, Fay Lords may not want their own troops Marked at all, despite the advantages of the Mark. More often, they won't want their neighbors' Marked.
More benign troops can "borrow" Adam's Mark off a guest, without absorbing them, as when human guests are asked to fight as champions in fay battles.
Some troops routinely collect neighborhood Trimmers when they die. Trimmers do not come with Adam's Mark, making them both less valuable and less troublesome.
For people seeking to join the fays voluntarily, joining a troop is much the easiest way to do so.
When a troop gets trooping, it is hard for anyone concerned to keep track of time. Even if you have not been joined to the troop, but are just on the fringes (the state of people who are dancing "just one more reel" with the elves, for instance), a year can pass in a few minutes.
A single night of partying with the fairy court (a more refined form of troop), or a few months of their hospitality (and it can be hard to tell the difference between that and a single night), can mean centuries passed at home. Nothing to do but go back with the elves, as a rule. You were enjoying it, right?
The mortal recruited might have died somewhere along the line without realizing it, usually just before they embarked with the fays. These are the folk who vanish/crumble when they realize how much time has passed. They aren't fully materialized into faydom yet, or possibly not really assimilated to the troop, and just lose their manifestation in the shock of realization.
Wild Hunts happen when trooping boils over. Nevertheless, all fay societies include Wild Hunting troops, troops that do little but get ready for Hunts, Hunt, get over Hunts, and loaf. Trooping in general is a rush, and Wild Hunts much more so.
Fays in general like hunting—not Wild Hunts necessarily, just hunting—possibly because they are close to their hunter-gatherer roots, even if they generally live a life of magic-powered courtliness. Fays who are really keen on hunting, more so than their fellows consider normal, drop out of their societies and run off to join the circ....the Wild Hunters.
This does not necessarily mean being assimilated into a troop; the Wild Hunters may be fussy about who they let in, or be easy-going about letting people hang on the fringes, where they can run useful errands for the more deeply addicted. (Someone's got to do the fiddly jobs of training and feeding the flying dogs and horses, for instance.) But, then again, it may mean assimilation.
Fay Lords tolerate Wild Hunts in their domains because (1) it would be almost impossibly to root them out, (2) a reasonably clever Lord can aim a Wild Hunt at a chosen target, and (3) they are fun to join for a night, as much for a Fay Lord as for anyone else.
Herne the Hunter was born human, became a fay after death, and is now the lord of a famous Wild Hunt. Such is his force of will, he joins and leaves this troop at will. When he leaves, he takes the bulk of their leaven with him; this is one way he controls them.
Wild Hunts are an Unseelie invention and custom, and most widely practiced in the Unseelie Court. The Seelie Court does Wild Hunting less often and never goes after human prey.
At the opposite pole from troops of fays living under the rule of a Fay Lord, there are the nature fays, living solitary lives in wilderness. They are members of the Wild Courts only if you insist on classifying all fays into one of the three groups; they don't consider themselves members of anything. They are often unMarked.
Many are just pre-Adamite hominids plus magic, and very little more. The magic makes life in the wild easy, and that's where many of them leave it. If they go further, they generally develop thematic magic focused on some living thing—a species of animal or tree, usually.
Some have just been this way for ages, since their death. Some are exiles or expatriates from fay societies. Almost all intensely wish to be left alone.
One way of winning Adam's Mark is by taking service with a human household. It usually takes a long time, but fays have a long time. Every night, when the brownie settles down to eat its bowl of oatmeal or milk or whatever, there is a tiny chance that they will get Marked, a chance which gradually grows as the years go by.
But it is now pretty generally known that giving the brownie clothes, or sometimes naming it, also Marks it. I don't know why they have to leave when they get the Mark, but they do. The brownie may be glad to leave, or not, as shown when it makes its adieu.
Just as there is a thrill to joining a Wild Hunt, there is a thrill, like unto a gambler's, to think that maybe, just maybe, tonight there will be Adam's Mark at the bottom of the oatmeal bowl. The process can become an addiction, as any gambling can be. By a process of transference, any oatmeal (or milk or whatnot) becomes a compulsive habit. This leads to the sad institution of Oatmeal Dens.
Perhaps the un-addicted brownie leaves rejoicing because he has the Mark and has reached his goal, while the addicted leaves complaining because now the wonderful game of Oatmeal Roulette has been cut short.
Brownie-duty was invented by the Seelie Court and is commonest with Seelie fays. The Seelie Court sometimes sends fays to be brownies, in order to get them Marked. The brownies who show themselves and become members of the household are likely the Seelie ones. The reclusive ones that go poltergeist when crossed are more likely to be Unseelie. Wild Court fays can go either way.
Fairy godparents are from the Seelie Court, or very occasionally Wild Court or "free"/"rogue" fays. The Seelie Court ones are usually an outreach effort to Christendom. (Though there is a warped variation in which the godmothers' blessings are "payment" for taking changelings, either before or after the fact.) The Unseelie don't do godmothering; it involves too close an association with human religion.
The blessings cost the godmother leaven, not just prana, so it is a costly gift. On the other hand, she gets Adam's Mark, for herself or (much more commonly) to pass on.
Tales of fairy godmothers leak through the Sundering from Cryptic or other Abscondian nations.
The bad fairy, if any, may be:
There are also occasional fairy godfathers, but they almost always work singly, not in teams, while godmothers may do either.
Fairy patrons are the reverse of brownies, where the fay is in the dominant position. The patron rarely employs a mortal as a full-time servant, but the two trade favors, and the favors of the fay are usually life-changing for the mortal, even if they are small change for the fay.
The big benefit for the fay is that, in the process of one of these transactions, the patron may get a Mark. Usually, the patron already has a Mark of their own, but if they are adhene or sidhe, or have the blessing of one, they can pass the mark on to another fay of their choosing.
If the patron is Unseelie, they don't really want a Mark, but they can trade it to someone who does.
Changeling swaps are very tempting for any fay community. Not only do you get a new recruit, but if you hold off on the Fairy Marking and let them stay mortal for a while, they can breed fays directly.
Fays of all courts do changelings, but you won't get your baby back from the Unseelie. They swap it for a stock, which appears to die, and that's that. The stolen babe, meanwhile, is immediately joined to a troop that the Unseelie control but never join, turned fay, then often made into something useful, like a (humanly intelligent) dog or horse or the like, to be raised up by earlier captives.
Seelie changelings are fay babies or impostors. You might get your child back, if you make it plain that you have discovered the swap, or by mistreating the changeling. For the Seelie, the best situation is a fay baby successfully swapped. The Seelie get a human child to Fairy-Mark (perhaps after they have raised up a Markable family with a fairy spouse), and meanwhile the fay baby grows up in the human world and, with moderate luck, gets Adam's Mark by baptism or something similar, then has children. Somewhere along the line, the changeling learns what they are (probably as soon as they can understand, getting immediately slapped with a secrecy geas), and has had children that they take along into Faerie. Maybe even their spouse. What a deal!
Wild Court fays, of course, may use either set of tactics.
The midwife stories are much as people have thought about them: fays call in human midwives because they are not at all experts on birth, and the midwives generally suffer from the dangerous company.
Their clients are women who are not yet fays or, more often, have not been fays long, since they would not otherwise be carrying babies. The father is a fay, of course, probably a Fay Lord. If he were not, he would be unlikely to be the head of household, as he is in the stories. Unless his headship is a sham, of course, or the "father" is playing a role and the real father is someone else. After all, shamming is central to the midwife stories.
Fairy troops want to capture humans to acquire the Mark. As soon as they can, they assimilate the captive to the troop, thus turning them into a fay. There are two main methods for assimilating a human: feed them enchanted food or keep them captive for a sufficient length of time. The first is actual use of a spell; the second is just sort of osmosis.
A captive is not really memory-wiped—once a being is a fusion of soul and body, it's virtually impossible to erase memories permanently—but the change of state plus the forcible entry into the common leaven store plus the abrupt shift to a new, hostile social setting with another species all means your old memories, and a lot of your old personality, just don't apply any more. New members often suffer PTSD and depersonalization. By the time these wear off, the old life is very far away.
Fays of any Court may take captives, but Unseelie never join the troops in which they install their captives; they just control the troops. Or they may keep captives unjoined and mortal, as slaves.
The story is very, very different for the occasional volunteer. The metaphysical changes are still a shock, but they go to a society that they generally know more about, a more or less friendly one, for which they did, after all, volunteer.
The lines between volunteer, captive, and changeling can be blurry:
"Come away, O human child!
To the waters and the wild
With a faery, hand in hand,
For the world's more full of weeping
Than you can understand."
Trimmer fays are basically the same as captives and volunteers, only they start out dead, as ghosts. Also note that they no longer have Adam's Mark and will never get it back.
Since they become fays, fusions of soul and body, they must acquire body. These are airy, ectoplasmic bodies, even small ectoplastic bodies. These may go on to grow or solidify, or they may not. All fays are shapeshifters, so change is always possible. But not all fays are equally good at shapeshifting or learn it equally fast.
A large number of Trimmers are fairly happy about their situation, if they understand it. It is, after all, a lot better than going to Hell.
Taking captives and Trimmers is basically a Seelie move. They want to cozy up to humanity and this is a good way to do it, in their opinion. Unseelie may consider taking Trimmers to be "poor form," but it can happen, usually if an Unseelie court or lord has a reason to acquire this specific human, and especially if they have a separate tame troop to put them in. Then ideology be damned. It's not like there was any Adam's Mark to worry about.
Sometimes a fairy lover is just a fairy lover. A good time is had by all, and that's that. But it's a grand opportunity to get a Mark if you need one, for yourself or for someone else. For less loving lovers, sans merci, it's a chance to strip off leaven, too, and leave the mortal "alone and palely loitering." Both Seelie and Unseelie can become fairy lovers, though it's commoner among the Seelie and the leaven stripping is commoner among the Unseelie.
These ladies have lost a bet. A mortal hero has asked for their hand and they, or their lords, have set him a task, or three, or seven (which is considered excessive in the circles that evaluate these things), and he has done them. She is then contractually obligated/geased to wed him. And to look happy about it. This is easier than it might be, since he's mortal and she's not, and anyway he's almost certain to break the condition that's part of the contract. Also, by wedding him, she gets a Mark to keep or, more usually, pass on.
She may also get children out of this, naturally Adamite, but easy to Fairy-Mark.
Only Seelie and Wild fays play this game. Unseelie do not.
Folklore is full of special fay vulnerabilities. If these are real, they usually spring from one of three causes:
Being as much spirit as body, fays are readily exorcised by even feeble appeals to human religions. It does not matter much if the religion is theologically correct. Being Marked and a member in good standing of a religion generally fixes this. Being an adhene or a sidhe does not; their "family" ties to Heaven are lukewarm at best. (But remember that exorcism works at Heaven's discretion. A scumbag human cannot best a decent fay just by pronouncing "Ego te exorciso in nomine Patris et Fili et Spiritus Sancti." As Puck himself observed on such an occasion, "I was as good a Christian as him any market day.")
For a common un-Marked fay, any religious stuff has a terrifying Lovecraftian vibe of incomprehensible infinitude. Marked fays are another matter, but even they may still have ages of dread and superstition to get over.
In lieu of actual conscience or bodies of law, common fays are often regulated by their lords using systems of oaths, geases. Even if the fay gets Adam's Mark and an actual conscience, the geases don't go away. As a result, the fay may be bound to take any offer given during a revel, or stop and count all the beans in a pile, or something of that sort.
Fays are not necessarily well-informed or even rational, so they may be quite superstitious themselves.
It was a mountain of centuries sloping up from the highest antiquity we can conceive, up and up like a mountain whose summit never comes into sight, not to eternity where the thought can rest, but into more and still more time, into freezing wastes and silence of unnameable numbers.
—That Hideous Strength, C. S. Lewis
Common or Angelblood fays have a natural ability to shrug off arbitrary amounts of time. If they've spent a hundred millennia in the same forest and most years have been pretty good, that's okay. Ex-mortal fays begin asking "Is this all there is?" and getting existentially bored and restive. On the down side, they can start causing trouble. On the up side, you can often enlist them for all manner of unlikely causes. "Want to squeeze all the indigo out of the rainbow?" "Sounds ridiculous. Sign me up."
Trimmers (q.v.) are another matter. Trimmers are damned, really, just damned lightly, not let into Heaven but left inedible to and indestructible by demons. Trimmers are more truly ex-human than other once-mortal fays because they have lost Adam's Mark and can never get it back. But no, they don't cope with long periods of time any better than other Mortalborn fays, at least not until they have been further dehumanized. The ghastly thing about being a Trimmer is that, within broad limits, God doesn't care what becomes of you.
If Trimmers evolve morally, they do not do so as Children of Adam, and that takes a lot of the impetus out of that evolution.
The non-Trimmer Mortalborn can't get to Heaven or Hell but they are not moral ciphers. As they cope with everafter and find it inferior to eternity, they tend to move in one direction or another and, after a few centuries, wind up (or not wind up—they can't "wind up"—say "become") really saintly/angelic good fairies or really devilish bad fairies. At Kingdom Come, they will be saved or damned, but until then they are stuck in the material realm. The same applies to fays who were never mortal.