Adva'relle, s. 19 was born into the Tide, on the Island of Rouw. Her father, a great Listener, brought her to Blue Spoon as a child. He believed that she was meant to be a Priestess of the Lost, and as he held power within the community, that is what she became. Adva joined the Priestesses at seventeen, and became fully initiated at nineteen, when she received her Shell.
When Adva becomes a Priestess of the Lost, unbeknownst to anyone, the shell that she is acquires during her initiation contains Cerulean, a powerful AI Aggregate Personality designed by the Blue Rose Group before the Last Fall. The shell is prized because it is mostly intact and uncorrupted, and seems likely to give Adva a long life before it blackens her, but it isn't believed to be particularly powerful at all. However, the more intense and emotionally demanding Adva's battles and experiences become, the more Cerulean begins to physically manifest in the world.