Affinity

Every living creature has a soul granted by Tey'Kor-Akx. The entities called souls are in fact mere fragments of the Over-Soul, a treasure pulled through the Void from a previous world by the Ineffable in an effort to defy Oblivion. The Over-Soul is known to have brushed up against the body of each Primordial, and carries within it an aspect of each.
When a fragment of the Over-Soul is granted to a living being, it is inevitable that the fragment contains a greater degree of influence from one Primordial than from the others, and this is the soul's Affinity. Affinity results in the base temperament of an individual's developing personality, and while it does not define their moral and ethical outlook (all newly integrated souls start out as colourless), it does define their approach to relating to others. There are 9 Affinities, one for each of the Precepts outside of Space and Time.
Oblivion
Oblivion is defined by its perfectionism and desire to create an ideal world, and those whose souls have an Affinity for the darkness have similar proclivities.
Mithras
Mithras is defined by its leadership and desire to build defences against darkness, and those who have an Affinity for the light have similar attitudes.
Nito
Nito is defined by its loyalty and desire to test the character of mortals, and those who have an Affinity for the stone have similar proclivities. 
Dagon
Dagon is defined by its observance and desire to understand all reality, and those who have an Affinity for the water have similar attitudes.
Urana
Urana is defined by its helpfulness and desire to express its benevolence, and those who have an Affinity for the air have similar proclivities.
Ignis
Ignis is defined by its passion and desire to maintain its freedom, and those who have an Affinity for the flame have similar attitudes.
Sif
Sif is defined by its status and desire to become distinguished, and those who have an Affinity for the cold have similar proclivities.
Dr'Oon
Dr'Oon is defined by its imagination and desire to express itself, and those who have an Affinity for the dream have similar attitudes.