Covenants
A covenant is a political and philosophical allegiance — chosen, not inherited. Where a clan is a matter of blood, a covenant is a matter of belief and ambition. Kindred join covenants because they find in them a worldview that matches their own, or because the covenant offers something they want: power, community, knowledge, or purpose.
Covenants are the organisational layer of Kindred society. They have hierarchies, expectations, and responsibilities. A Kindred's primary political obligations run to their covenant, and it is through covenant membership that most Kindred engage with the broader politics of a domain.
Allegiances can and do change over a lifetime, though leaving a covenant is rarely without consequence.