Ether

Ether is a white, gaseous substance that Fallen depend on to survive, and which only Servitors can currently produce.

Overview
Once freely available on the Fallen homeworld, it is now strictly rationed according to rank, limiting the strength and possibly the size of contemporary Fallen. It is absorbed by breathing and appears to run through Fallen bodies like blood. Servitors convert scavenged matter and energy, particularly organic compounds, directly into Ether via an unknown process. Ether Seeds may be processed Ether for later usage or storage. Killing Fallen with headshots causes a torrent of ether to erupt from their heads. In Destiny 2, this takes the form of a momentary, ghostly silhouette of the dead Fallen.

Enhanced Ether
During the Red War, the Fallen House of Dusk was able to utilize stolen Cabal technology and the Servitor Serkuleks, the Fount to create a modified, more effective form of Ether known as "Enhanced Ether". Those who took this Ether substance would become Empyrean Fallen, exhibiting several effects including increased strength and health, and the side-effect of glowing blue. Raksil, Archon Priest would head this operation before being killed. The project would later be put to a complete end following the destruction of Serkuleks at the Guardians hands.

List of appearances

 * Destiny
 * Destiny 2