Otherworlds
The lands and waters of the Archipelago make up the waking world. It is vast and strange, filled with magic and mysteries, but it is nonetheless a world that is concrete and tangible. The sun rises and sets, the seasons change in a predictable pattern, and the laws of cause and effect are not easily bent.
There are numerous otherworlds that exist in the shadow of this waking world. The strider enclaves are one example of an otherworld; the dreadful Garden Wall is another. These otherworlds are visible from the Archipelago as the stars that fill the night sky, remote and mysterious. Where the waking world is concrete, the otherworlds are abstract. Concepts and ideas hold more sway than causality, and the laws of mundane reality are malleable.
Each of the otherworlds embodies some abstract concept, often rooted in the forces of nature or the collective will of the Archipelago’s inhabitants. They are chaotic places where the abstract crashes against the mundane, straddling the divide between what is real and what is not. Physical laws and space are elastic. In such places, words can bind and the boundary between dreams and reality is thin. An otherworld follows its own rules, and no two are alike.
The Sun and Moon
The Sun and Moon mediate the boundary between the waking world and the otherworlds. Strange and otherworldly powers are always weakest by the light of day, and sunlight burns away naked spirits if they do not have a vessel to house them.
While the Sun rests from its labours, the Moon opens a hopeful door to the infinite possibilities of the far and strange realms that lie beyond the waking world. The waxing of the moon thins the boundary between the worlds. Entrances to the otherworlds only fully open when the moon is full and showing its face.
No one is quite sure what the Sun and the Moon are, or how they came to be. Some believe that they are, both of them, alive and aware. If this is true, this awareness must be a vast and inscrutable one. You cannot speak with the Sun or the Moon, but students of astrology seek to glean wisdom and guidance from them all the same.
Spirits
The native inhabitants of the otherworlds are called spirits. Like the otherworlds themselves, they are abstract beings. They follow strange laws, possess strange powers, and are born from thoughts, ideas, dreams, and energies. Their physical shape and their inner nature are one and the same. If their emotions or desires change, it is often accompanied by dramatic changes to their appearance and form.
Spirits are immortal. They can die, but it doesn’t usually stick. Under normal circumstances, a spirit can only really die if it no longer wishes to live, so emotional injuries are far more lasting and impactful than physical ones. A spirit can hold a grudge for a long time, and a festering bitterness can quite literally transform them into something very different. Likewise, a spirit that has been dead for a century might be convinced to live again by the right person.
Spirits can exist in the waking world. It’s not simple for them to enter it, but it is possible. They can come when summoned, or by certain special paths under the light of a full moon. They can even cross the chasm of night and plummet to the world as falling stars.
A spirit in the waking world is very different from the beings of power and strangeness you’ll encounter in the otherworld. As abstract beings, they usually cannot take on a physical form. They come to the Archipelago as invisible and insubstantial shades, limited in their ability to affect the waking world. These unclothed spirits cannot withstand the pitiless light of the sun; it will burn them away, destroying them forever. If they wish to remain in the waking world for a long time, they must find a vessel to inhabit.
Inhabitation
When a spirit comes to inhabit a person, we call that possession. An inhabited person gains strange powers from their passenger, but they also undergo physical transformations. These powers and changes grow as the spirit continues to inhabit you, as does its presence in your body and power over your mind. The stronger the spirit, the faster this happens. Inhabiting spirits that make a habit of outstaying their welcome are known as demons.
When a spirit comes to inhabit an object, we call the object a redoubt. They rarely do this willingly; most inhabited objects are the result of desperation or occult binding. Like an inhabited person, inhabited objects often possess strange powers related to the spirit that dwells within them. The one who wields or touches the inhabited object can converse with the spirit within; if the object has not been prepared with special wards, they may even be possessed.
When a spirit comes to inhabit a place such as a river or a forest, we call them an elemental. Such spirits become one with the place they have chosen to inhabit, making themselves a part of the waking world by wedding themselves to it. When angered, they can rouse the fury of the elements against those who trouble them. You’re more likely to find places inhabited by elementals near the entrance to an otherworld.
There is a fourth and final option for spirits that wish to extend their stay in the waking world. They can cross over fully, entering the waking world in their physical form rather than as an insubstantial shade. Such embodied spirits are powerful and dangerous beings, as potent in our world as they would be in theirs. To do this, however, they must give up their immortality and become a mundane being. Many of the monsters and strange entities that fill the Archipelago are descended from spirits that made this choice.