On Elves

Elves of the Orrery are not the Elves of Tolkien, rather they are more accurately Changelings. (This idea is stolen whole cloth from Ten Foot Polemic: here, here, and here). They are intimately connected to the Fey.

Elves

Elves, as a whole, are pretty wondrous beings. They live and breathe magic to a degree unimagined by those who devote their lives to study. Magic to them is a natural thing, especially that magic which is their heart spell, that which was inscribed on their soul. This soul spell will determine largely how the Elf mutates as it grows in power, however all Elves have a few things in common.

What do your Elf Eyes see?
Elves are preternaturally alert, can see further and listen more keenly than humans, giving them +1 to their awareness.

Nasty, big, pointy teeth
Every Elf grows some sort of natural, generally animalistic defense. Sometimes this manifests as over-wide maws stretching across their faces and filled with savage needlepoint teeth, or their fingers elongate into razor sharp birdlike talons, or their bodies produce crystaline shards and carapaces of diamond hard rock, or maybe they just have, like, Wolverine's claws or something. In any case they have a bonus to hit and to damage of half their level.

Born of Magic
All Elves are natural magic users, they have a particular spell inside their heart that was sung into their bones at the moment of creation. They can always cast this spell, without spell slots, or mana, or anything. They speak to the world in the language it understands, and it always answers. The essentially human frame that is an Elf is too frail to hold more than one spell, so additional magics are learned in the same way that other magic users have to know them. This heart spell is a first level spell chosen (or randomly generated) at first level. This heartspell will begin to seep out into the world as the Elf grows in power, routinely generating minor magical effects around the elf related to their heartspell.

Changelings

Any similarities to existing games is purely coincidental. When someone is kidnapped by the Fey, they leave something behind in their place. Sometimes it is a simulacrum which believes itself to be the real person, sometimes a pale imitation which dies within days of the abduction, sometimes they are replaced with one of their own.

Not only do Elves return to their homes with a great deal of time difference (sometimes several centuries pass whilst they believe that they have been merely enjoying an evening of entertainments) the Elves are marked by their time with the Fey, magic inhabiting their very souls. Whether this be from a carelessly sung Fey song settling its magic deep into the bones of the visitor, the food of the Fey changing and binding their soul, or the Fey themselves vivisecting them for fun and writing a spell on their heart before sewing them back up and kicking them out. In any case, the experience invariably leaves the Elf incredibly traumatized, the lack of the knowledge of the song leaving a hole in their heart so deep that they will grieve forever at the loss and wish only to hear it once more, the taste of all other food turning to ashes in their mouths in comparison to the indescribable essence of true flavor, or waking up in cold sweats every night with the image of their own still pulsating organs laid own before them as a mad eyed fey looms over them coldly glinting scalpel in hand.

These are the most pitiful of all the Elves, often with no idea of what they have become. They return from their confusing and terrifying sojourn in the other lands changed often into bestial and terrifying forms. They return having been separated from their friends and families often for years (from one or the others perspectives), and even if they retain their human forms, they will never be at one with their people again. There is always something left in these Changelings of the wildness of the otherworld, a sort of extra depth of understanding. They will always add their level as a bonus to any check involving the wilderness and animal handling. 

Fairchilde

When a beautiful Fey wanders into the mortal realm, it is all too common for their weird and protean beauty and otherworldly air to ensnare the hearts and minds of many whom they encounter. If the Fey finds this mortal sufficiently interesting, yet for some reason does not immediately spirit them away to the Fey realm, they may end up with a souvenir from an evening of weird passion. The Fey have no clearly defined form or gender, and so may be the mother to one Fairchilde and the father to another.

A Fairchilde will not always know their nature, although they will certainly not know one of their parents. Sometimes their Elven nature will manifest itself at puberty (X-men rules, woo!), although a few especially unsettling Elves manifest their powers as children, and often retain that shape for their entire existence. Mostly, however, the expression of their Fey heritage will lie dormant in them for many years, although they will age much more slowly than their contemporaries, often appearing to be in the prime of youth well into their fourth decade. In these cases, it is often set off either by an encounter with the Fey (especially if their wayward parent appears to see how their young offspring is faring), or with some other incident of a magical nature.

The Fairchilde Elf will never become a true Fey (without finding some form of fire to burn out their mortal half), but their blood sings with magic and learning spells comes to them much more quickly than to humans. They will learn and transcribe spells in half the time it would take a human and add their level as a bonus to any check to understand magic or magical effects.

Ælfen Koenig

Inspired by the Late Great Galaxy Johnson of Ten Foot Precis. This is what happens when one of the Fey trapped in a crystal leaps out and takes control of a human body. These Elves are the most dangerous of all, for they have the potential to become as powerful as a true Fey, that is: Godlike.

Whilst initially no more powerful than the other sorts of Elves, as these folk grow in power in a different way. Their heart spell grows and changes with them. Instead of learning other spells, the awakened mind of the Koenig learns to change their heartspell subtly in order to accomplish different things. In rules terms it means that you cannot learn any spells which could not conceivably come from a change to your heartspell. A Koenig whose heartspell was sleep could perhaps draw on the power of dreams to create illusions, and conceal themselves in invisibility borne of half drowsy minds, but they could not learn how to shoot real fire from their hands or anything. A Koenig can only know as many spells as it has levels, however all of their spells count as Heartspells.

A Koenig, at the height of its power, is a terrible and splendid creature. Bound to the mortal plane, but instinctually speaking the language of the earth. No power is truly beyond its grasp.