If she finds out that fact before actually meeting him and Rizhao, expect her to call him "Your Grace." ... Or, uh, Mako Rizhao. Because Rizhao would totally be his dragonsoul, right? ...right? It's only polite to acknowledge both halves! XD

Of course, that's how Dragonlords are addressed in her world (excepting if the Dragonlord gives permission for more informal things). The confusion and culture shock will be delicious.