Ar'alani is a Chiss admiral of the Expansionary Defence Fleet, created by Timothy Zahn for Outbound Flight (Del Rey, 2006) and made a lead character of the canon Thrawn Ascendancy trilogy (2020–2021).
The uniform tells you the arrangement. Chiss officers wear black with shoulder patches in their ruling family's colours; Ar'alani wears plain white, because members of the Defence Hierarchy at her level relinquish family standing to serve the Ascendancy rather than a house. In a civilisation organised entirely around family patronage, she is the person who stepped outside it.
She is also Thrawn's closest peer and the only officer in the Ascendancy who both understands his methods and is prepared to stop him. Zahn writes their relationship as a long professional argument between two people who like each other — she is the friend who says no, which is not a role the character usually gets in this franchise.
She appears in canon in Thrawn: Alliances (2018) and in the Thrawn Ascendancy trilogy. The Legends and canon versions share the rank, the uniform and the relationship; the details of her career do not carry across.
