One's affiliation describes their standing (or lack thereof) as a member of one or more of Nodd's houses and cults. Joining a house or cult is commonly seen as the primary way to learn powerful magic, though it requires dedicating oneself to the given faction's particular way of thinking.
In almost all cases a citizen may only be the member of one house at a time. Leaving one house for another is not unheard of, but it is very rare to be welcomed back into a house after leaving. However, a citizen may be a member of a house and one or more cults at the same time depending upon the exact situation.
Many citizens consider themselves "unaffiliated", choosing not to have an official tie to any one house or cult. Houses and cults will still gladly do business with an unaffiliated citizen, however. Saying one is "affiliated" with a faction doesn't always imply membership, and can also mean a given citizen simply agrees with a certain faction's ideologies or manner of conduct.
Joining a Faction
If one were to wish to join a faction the most common method of making contact would be through an initiation party. Held frequently by Houses and cults alike, these gatherings serve the dual purpose of fostering wide-spread belief in the faction's magical prowess as well as reaching out to interested initiates.
When seeking to join a house or cult, the would-be mage has a handful of options. Houses in particular offer three relatively standardized methods for joining: completing a trial, offering suitable tribute, or enduring apprenticeship. Cults, being less regulated than houses, tend to have more varied methods of joining.
Trials
A newcomer to a house may opt to attempt a trial, a potentially deadly task assigned to them by one of the house's savants. Many savants use trials as an excuse to haze newcomers, offering tasks that are impossible or intended to humble the newcomer. Given that most savants would rather have the prestige of an apprentice studying under them, trials tend to be unappealing by design.
Tributes
A newcomer who proves resourceful enough may skip the need for other tests entirely by making an ample contribution to a given House (or, at least, the correct members of said House). Sometimes membership in a House is given as repayment for a favor owed by the House.
Apprenticeships
The most common route towards becoming a house member. Apprentices study under a savant for a full turn, obeying their every command. While the Savant is free to abuse this relationship as they see fit, the experience a given apprentice has varies wildly. A fair amount of slaves in Nodd are actually apprentices studying under their chosen savant.
Given the incentive a savant has to take apprentices, many will pressure a newcomer to choose this option unless there is a chance of a significant tribute.
Disciples
A disciple is a member of a house or cult who has completed one of the above methods and gained full membership within their chosen faction. While ranked above an apprentice, a disciple does not have the privileges afforded to one who has undertaken the Final Rite and become a savant.
Final Rite
The Final Rite is the barrier between a disciple and a savant, and conquering it is typically the primary goal of a given house member. It is a trial unique to each house and cult, carefully crafted by the most powerful mages within said faction to serve as the true test of a mage's capability.