Those opposed to Seelie rule or who insist upon more freedom follow the Unseelie. Choosing a court merely indicates which one you follow most of the time. Deciding which Court you belong to also indicates which Legacy you generally follow. Legacy Legacies are tied to one court or the other and describe the two fundamental sides of your personality. If your Seelie side is dominant, your Seelie Legacy is too, with your Unseelie Legacy lying dormant just beneath the surface.
Legacies are detailed in the core rules.
Seeming Your character's seeming reflects her mortal age and provides some of your characteristics. Tempers are covered later. House Sidhe nobility are divided into five noble houses, each of which holds a different philosophy and imparts a certain reputation to its members. Being part of a specific house also bestows particular Boons and Flaws to the character. Only sidhe are considered true nobility and able to belong to houses.