The Dia-Fotizo, or as many members call it, the "Fatizum", Is a collective of immortals that spans back across time for millennia.
While most of it's members simply use it as a means to keep in contact with other Immortals, using its resources once every few decades; there are some who have devoted more of their time and energy within it's membership.
Over the centuries devout members of the Dia-Fotizo have created and congregated into three main Subsections, houses, guilds, or whatever word may be fitting; The Kynigos, the Logios, and the Anoterum .
Each have their own designs, goals, and functions in the world, and amongst it's peers. Each provides it's own resources to the members, or requests varying things from them as well. The Kynigos might want help tracking down a creature of The Long Night ; a member of the Logios might want help acquiring some harder to find antiques or manuscripts; whilst the Anoterum very well could require a small town to go without supplies for a month.

As New members of the Fotizum, you are among the lower ranks, not much power in the collective, but still a member, and able to grow and utilize it's resources (within reason, of course).
There is no "headquarters" nor guildhall, the Fotizum is fairly self governing and spans across the known world, usually using the higher ranking and older members resources and lands when gathering is required. The exception to this is the Kynigos , who have a main Hall, called the Hall of Resurrection, where it keeps the totems of all who devote themselves to the Kynigos house.