Pae Halka and Pae Shulk

The world of Paema'ana, as imagined, is a mirror. On one side, there is the human world Pae Halka, on the other the fey Pae Shulk.

Magic is persistently present on both sides and studied at the Arcanums spread around the Paes.
Science is studied at the Eksperimenta, also around on both sides.

Neither side's normal inhabitants are aware of the other and most just live their lives in blissful unwitting normality, but those that are aware may know some key rules that bind all who live on the mirror.

On either side of the Mirror, a stream of souls is tallied into a conglomerate known as the Veil.

From the Veil are drawn the souls of those who died to re-inhabit newborns on that side.

This tallying of souls is known as the Balance and it is inescapable.

To cross from side to side, one can use the five main 'Gates' (elemental aspected portals). These open twice every year. Five times only one opens and once each year all the gates are open at the same time. Rarely does another portal open, but all the rules remain as below, each day.

At midnight's toll, the Balance is made and those who crossed over to the other side and remained there are subjected to one of three fates:

a) The Monsterous Shifting:

Happens to those not native to the side they are on if the tally is balanced.

A loss of memory, form and a slow mutative growth in power.

Most who suffer this transform into beings known as 'monsters' and wander the wilds, being feared and hunted until they meet their demise or establish themselves as immortal legends.
They can still hold some memories from their old life, but these usually manifest themselves in a strange sort of madness. Should all memories fade, the soul will rejoin the Veil and only a feral being will remain.

b) The Linked Pact:

If a linked soul crossed over at the same time or if a pact has been made, one can cross into
the other side with only temporary inconvenience.

Two months of rest and recuperation restores the memory to the ones who crossed.

(This coincides with the festivals marking the opening of the Gates)

These are exempt from the randomness of the Balancing as long as their linked soul is anchoring them from the other plane.
Once the linked soul dies on the other plane, mutation sets in and the crossed figure will
become subject to mutative degeneration into a monsterous form, becoming a fantastic
archetype like The Dragon or The Mermaid. Their soul, however, remains with them.

c) The Balancing Curse

Happens to those whose numbers exceed the allotted souls.

Passing through a Gate but failing to return in time violently thrusts the excess Crossers back to a matching spot on their original side, with their memory disrupted and all their possessions scattered. The usual result is death.
This makes for excellent fodder for those that would want to harvest souls for their own goals, or recovering bodies to be used as 'troops'.

"Zombified"soulless bodies can cross and carry out simple tasks. They can be trusted with tasks up to random kidnapping and fighting, but not diplomatic missions.

The Day / Night cycle.

Pae Hakla:

16 hours of daylight before the Veil is lifted to shroud the land in a silvery darkness for 8.

Pae Shulk:

16 hours of twilight before the Veil is lifted to illuminate the land is a silver glow for 8.

The Seasons and their respective months are

*Byan'qe [Festival]
-Ferhe [Harvest]
-Appex [New Year]
* Meht'ion [Water]
-Kevee [Flood]
-Antóat [Ebb]
* Abla'al [Fire]
-Shach [Kindling]
-Faness [Glow]
*Rapan'qe [Soul]
-AuÝadin [Introspection]
-Piness'te [Grieving]
*Ver'Za [Earth]
-Harwer [Sowing]
-Aitnem [Care]
*Uhf'ah [Air]
-Temph [Storm]
-Exogh [Breeze]

The gates are:

1) The East Gate (Water) - The Shrine (Torii)

Flotilla around the Gate

Underwater city

[Pae Shulk: The Whirlpool]

2) The South Gate (Fire) - The Forever Fire

Dwarven industry

Magitek 'Vulcano' fortress around the Fire

[Pae Shulk: The Blazing Rift]

3) The West Gate (Earth) - The Pyramid (Aztec)

Declining society

Earthquakes

[Pae Shulk: The Evercrater]

4) The North Gate (Wind) - Spire

Science-oriented society

Fragile airships

[Pae Shulk: The Whispering Reeds]

5) The Mystic Gate (Soul) - High Court

Elemental Chains hold down the floating Citadel

Melting pot with varied races

[Pae Shulk: Low Court]

Races are varied in the world, and it is commonly understood that living in proximity to the Shrines means more mixed bloods happen (This is actually the result of a Curse by the Lich). This can express in forms we would associate with dwarves (fire gate) / elves (air gate) / naga (earth gate) / nymphs (water gate) / spirits (soul gate).
The mutation into these forms is not as aggressive as during the shifting, but quite insidiously seeps into those that dwell in the vicinity of the Gates. 
It has become so normal to these individuals that most see themselves as a different race altogether and behave as though removal of the Curse is a disaster, linking it with mutation and degeneration into humans. 

Powerful beings known as Powers either settle near the Gates for this specific purpose or hide out in the wilds away from the Gates.

Known Powers and their suspected location are:
*The Dragon (High Court)
*The Siren (Las Remblas)
*The Dwarf (The Forever Fire)
*The Mermaid (The Shrine)
*The Recluse (travels Pae Shulk)
*The Knight (The Blazing Rift)
*The Changeling (travels Pae Halka)
*The Merchant (Low Court)
*The Demon (under Giza)
*The Lich (formerly Low Court)
*The Naga (Earth Shrine)

Why is control of the gates important / what goods are traded?

Fae world: Mushrooms instead of trees -> needs wood.
Due to semi-perpetual night, low amounts of wheats and similar foods.

Human world: Precious metals are rare -> Gold/Silver/... are seen as highly valuable.
Due to semi-perpetual day, medicinal herbs are in low supply.