Hearthstone

The magic of Hearthstones is what allows the Fae to settle Demesne in the ever-changing realm of Faerie.  A Hearthstone hold a single Demesne to a relatively stable flow of time, and keeps the laws of physics and magic consistent within the Demesne.  They do this by tyingthe Demesne to the will of one or more sentient creatures.

The simplest Hearthstones have a single anchor, usually their creator, and stabilize a small Demesne, often no bigger then a single dwelling with a bit of territory around it. Such a Hearthstone is generally no bigger then a campfire or a small fireplace.

The most complex, such as the ones that stabilize the main holdings of the Seelie and Unseelie Courts are the size of bonfires, and require as many as eighteen anchors to hold the Demesne stable.

Creation

There are many variations of Hearthstones, and thus many ways of creating them.  The most common process for creating a simple one is described by Lady Airean Kyrenic in her as-yet unpublished memoirs.

I knew I would have to spend most of the year living within the demesne I temporarily claimed as my own, so I spent some time searching out a suitable demesne.  One that was small enough that I could walk the edges of it within a day or so, but that had ample resources, so that I would not have to travel far to get food.  I found a small forest, and after exploring it, discovered that while the trees were mostly conifers and birch, there were many berry bushes and ample non-sentient game animals.  I choose a clearing near the center, and prepared to make the Hearthstone there.
First, I gathered stones and dirt from various parts of the Demesne. I made sure, of course to have one from eight roughly equidistant points along the edges, marking them to be used to set the points of direction for the demesne once the hearthstone had been established.  I returned to the clearing and used these stones and dirt to build a circular hearth, inscribing each stone with magic to tie it to the part of the demesne it had come from.

I positioned the direction stones most carefully, and inscribed them with the extra magic needed to tie them to both to where they had come from and to myself..  When the hearth had been completed to my satisfaction, at least with the rough shape, I cast the spell to make it one stone and shape it fully to my will. 
  Normally, before casting magic as complex as the spell to make the hearth into a Hearthstone, I would have cast a circle to prevent outside energy from complicating what I was doing. However, the very nature of the spell requires that energy is pulled from the whole Demesne, and that energy travel to all parts of the domain, so as holding a circle around the whole of Demesne for the length of time needed while casting the spell itself would have been beyond my magical ability, I simply began to cast. 

I built a small fire in the center of the hearth using wood and kindling gathered from with in the Demesne, which I then lit using my own magic.  I chanted the incantations to define the area of the spell and to stabilize the rules of it existence to my liking sending the reserves of Glamour I had gathered before setting out on this endeavor into the fire.  I then added a drop of my blood and a lock of my hair, to tie myself to the Hearthstone as the anchor, making myself part of the Demesne.
As I finished casting, the disorientation of suddenly being aware of the entirety of the forest overcame me.  Fortunately, the awareness quickly passed to being purely subconscious quickly, for had any dangerous creature or worse a member of the Unseelie Court found me in that time, I would have been unable to defend myself.  The physical fire was gone, replaced completely by one made out of Glamour.

As I was exhausted by the casting,  I decided I would wait until the next day to send a message to my family and House, informing them that I had successfully made my Hearthstone, and must now only keep it going for a year and a day to be recognized as an adult. I was so tired, I simply cast a spell of protection around the Hearthstone, unrolled my sleeping mat, and went to bed.  I did not even update my journal as I usually do, waiting for the following morning.

—  Airean Kyrenic, circa 1502 CE

Obviously, not all Hearthstones are created exactly the same way, and different species of Fae have different rituals with slightly different requirements.  However, the general requirements for each step can be summarized thusly:

1. The material to build the hearthstone is gathered from within the Demesne it is intended to stabilize.  Each piece is tied to the area it came from, and the connection is enhanced magically. The eight cardinal directions must be tied to eight bits of material magically, and those bits must be placed in the correct orientation within the circular construction of the hearth in the next step.
2. The hearth is built using a combination of mundane methods and magic to fuse the disparate parts into a coherent whole, both physically and magically. 
3. This step varies the most.  A physical representation of energy in some form must be put in the center of the hearth. The most commonly used representation is a fire. In more complex versions, where there is going to be more then one anchor, a representation must also be placed at each cardinal point. For this reason, there is usually one anchor, or there are five or nine anchors.  There must always be a central anchor. Extremely complex Hearthstone spells may have more than one sentient being as an anchor for each point, but there must be some way of making them parts of the same unit.  The Seelie Court, for example, has a long history of using married couples at a single anchor point. 
4. The sentient being or beings that will serve as anchors must tie themselves to the representation of energy through some kind of symbolic magic.  In the most common variants, a drop of blood and a lock of hair is burned in the representative flame at the anchor point they will be securing. 
5. The final incantation is cast by all anchors, establishing the conditions of stability in their demesne, making any changes to the demesne they would like, and feeding the hearthstone the energy necessary to create and maintain that stability.  When enough energy has been fed, the anchors become one with the demesne, and are aware of the section of the Demesne they anchor subconsciously.
6. If the magic is successful, the physical representation of energy will disappear, replaced by a figure of energy in the same shape. The Hearthstone must be fed Glamour by the Anchor or Anchors to stay effective.  If it does not receive energy, once its Glamour is used up it will go dormant, and will have to be reactivated with another spell.  It is a bit easier to reactivate a dormant Hearthstone then it is to create a new one, mostly a matter of bonding new Anchors and giving it the necessary energy.  A similar process is used to replace one Anchor with another.

Discovery

Hearthstones are essential to being able to live in Faerie, and no one knows exactly when they were first discovered or how that happened.

However, the magic is constantly being improved upon, and their are many variations to it.  For example, Dryads and other forest Fae often use a variation where a tree is the hearthstone, rather then a stone with a magical fire resting on it.  

For those that do use a fire based motif for their hearthstones, the color of the 'flame' often reflects the demesne in some way. The flame in a redcap anchored domain is likely to be blood red, for example.

Access and Availability

Most fae are taught at least basic hearthstone magic.

Among the Sidhe of the North American Courts, creating a hearthstone and anchoring at least a small Demesne rite of passage that must be completed before being recognized as a full adult.  During the required year and day , the hearthstone must not be allowed to go dormant. The young sidhe is able to leave the Demesne, but many prefer to spend most of that time within the Demesne they have taken charge of, for fear of letting the Hearthstone go out.

Just because all fae are taught the magic, does not mean all Fae can use it. It takes an intricate collection of spells and requires patience, strength of will, and a great deal Glamour to make a Hearthstone.

Complexity

Even a simple Hearthstone is a fairly complex piece of magic. 

For a simple Hearthstone for a small Demesne with one anchor there are:

• spells that go into associating each piece of the demesne with the area it came from
• spells that go into marking the cardinal directions
• spells that make the hearth all one thing
• a spell that sets the conditions desired in the Demesne at the time of creation
• spells that establishes the anchor as the giver of energy and the real-time editor of the spell controlling conditions
• a final spell which gives it energy and unites the rest of the spells into one

For more complex variations, such as those with more than one anchor, which are necessary for larger Demesne, the magic is far more intricate, and may take several days, or even months or years, to complete.