Proxy

Proxies are human beings who are chosen to carry the full breadth of a god or other deity's power. In exchange, as the proxy inherits more and more of the god's power, they lose their humanity. The gods may choose any human being to carry out their will, and do not require the human's consent. Once a human has been chosen to be a proxy, they slowly lose their sense of self until nothing more than a shell remains.

All gods are able to choose proxies. Belkira and the Oracle also have the ability. It is unknown if other non-humans like Genosis and Menw can have proxies.

Proxies and Vessels
Proxies and vessels are very similar in the sense that they both sacrifice part of their humanity in exchange for serving a god. The two are distinct in three major ways: The vast majority of proxies were vessels first. Mordred is a notable exception, as he is a proxy but not a vessel.
 * A god can have multiple vessels, but only one proxy at any given time. If a proxy dies, the god can choose another one.
 * Vessels typically have normal outward appearances. Proxies are designated by brands, which vary from god to god.
 * Vessels retain their humanity, along with their human abilities. Proxies lose their humanity and become little more than shells to carry out the god's will, and as such they wield the power of a god.

Brands
All proxies are designated by brands, or physical markers of their chosen position. Brands typically surface when the proxy is in advanced stages of their possession, rather than when it first occurs. Each god has a specific brand, which appears on all proxies they choose. Alseid and Arethusa's brands are not known.
 * Setine's brand appears as an green eye on the back of the proxy's right hand, and a mouth on the back of their left. The proxy covers their mouth and eye with the respective hand, and Setine speaks through the new mouth. The proxy's original eye and mouth are sewn shut with a silver thread.
 * The Great Angel's brand appears as an extra pair of eyes located on the proxy's temples. Visually, all four eyes fall on the same horizontal line. Two bone stubs, typically each a foot long, protrude from the proxy's back, like the remnants of angel's wings.
 * Vega's brand appears as puppeteer's strings, which connect all of the proxy's limbs to a ghostly, child-like, featureless mannequin that dangles above their head.
 * The Oracle's brand appears as a third eye that opens on the proxy's forehead.
 * Belkira's brand appears as two extra pairs of eyes on the proxy's cheeks, below their original pair.

Notable Proxies
Notable proxies include: It is arguable that the Oracle was also the proxy of the Great Angel.
 * Seti Ridley, the proxy of Setine
 * Judah, the proxy of the Great Angel
 * Lyra Nazari, the proxy of Vega
 * Rosaline de Clare, the proxy of the Oracle
 * Mordred Pendragon, the proxy of Belkira

Trivia

 * It's not clear what happens to a proxy after their death. However, Belkira implies that since there's no fundamental difference between the proxy and the god they serve, the god re-absorbs their power from the proxy, and the empty shell with it.