Aether (エーテル, Eteru?) is the land's life force and the origin of all magic in Final Fantasy XVI. It exists in the earth itself and all living beings. Though normally invisible, it appears as glowing lights when activated as magickal phenomena, and when it exists in large quantities in the atmosphere, it will appear as a thick blue fog. Aether crystallizes into crystals and the Mothercrystals are enormous deposits of it; Cidolfus Telamon believes that the crystals are sapping the land of aether, setting in the Blight, an erosion of the land where the ecosystem loses its aether, resulting in an ever-advancing environmental disaster.
Bearers, Dominants, and some monsters mutated by proximity to aether[1] can manipulate the ambient substance in the environment to perform magick. Those unable to manipulate aether directly need to use crystals for magick instead, but as crystal shards (mined from the Mothercrystals) are becoming increasingly scarce, the populace resorts to enslaving Bearers and even Dominants to use as tools of everyday life from agriculture to industry to household chores to waging wars and healing. Both Bearers and Dominants are susceptible of using too much of their own aether when using magick, resulting in a phenomenon similar to the Blight of the land: their bodies will slowly petrify. This is known as the "crystals' curse".
Concentrated aether pooled on the land's surface due to imbalance of diffusion results in aetherfloods (エーテル溜まり, ēteru tamari?, lit. aether pools),[2] where the very air glows blue and those who breathe it are severely affected, their bodies crystallizing and their sanity eroding, transforming into ferocious beasts known as the Akashic. Bearers and Dominants have natural aetherial tolerance (エーテル耐性, ēteru taisei?, lit. aether tolerance) to aetherfloods,[3] but monsters and regular humans are quickly transformed, and the effects are irreversible.[4] Aetherfloods are highly dangerous, especially in confined spaces where the aether cannot dissipate into the atmosphere.
Several streams of aether were drawn towards Twinside after Ultima used the Mothercrystals' destruction to raise Origin from beneath the town.
Eikons are composed of aether; when they get damaged, they can repair their bodies by absorbing aether from the atmosphere.
Crystal fetters are special restraints against Bearers and Dominants that prevent aether from flowing through the flesh of the one being restrained, making them unable to use magicks.
Etymology and origin
"Aether" was first used for a similar magick phenomenon in Final Fantasy XIV. According to ancient and medieval science, aether, also spelled æther or ether, is the material that fills the region of the universe above the terrestrial sphere. In ancient Greek mythology aether was supposed to be the breath of the gods, which formed the air which mortals breathed. The deity Aether is the personification of this idea as well as the upper sky itself. Final Fantasy XVI has numerous Greek mythology influences.
Magic phenomena that manifest as gaseous or liquid or crystallizing agents are common in Final Fantasy, having been called Mist, pyreflies, phantoma, and Miasma, among other names.