[X] Far East
Although from here, it might be more accurate to call it west. All of Ulthuan's trade with Nippon, Cathay, and Ind passes through the Citadel of Dusk while outbound, and half of it returns through the Citadel too. This means the Citadel would directly benefit from boosting interest in the exotic treasures of the Far East, and could be encouraged to take an interest in your museum gathering demonstrations of them. Increasing their involvement in the Asur trade network would also bring them into closer contact with the network of Asur trade colonies and outposts throughout the world, which could have all sorts of uses.
Affinity: Cathayan, Nipponese, Indic, and Khureshian Treasures
Bonus: Patron can contact Asur trade colonies and outposts
[X] Citadel
Though they were unknowingly your opponents for this adventure, there's no need for the military half of the Citadel to be your enemy. If part of your harbour were turned over to the Asur to act as a supply dock for them, then not only would they have a vested interest in the island remaining under your control, but it would also mean their seagoers would become a regular presence on your island.
Affinity: Ships and Naval Weapons of Naval Powers
Bonus: Asur have a vested interest in defending Fire Serpent Island