The Tokai Twins
They were inseparable as children, and even after they started being given separate lessons/training, they spent as much time together as possible, telling each other everything and sometimes dressing up as each other and switching places to attend each other's lessons or otherwise go off where they weren't supposed to be. Hiro is next in line as the heir to the Teng lands, after his father, but the twins always assumed they'd rule together when the time arrived. When their parents sent Hana away to the Hon'eth Arcade to train as a geisha, Hiro refused to stay home and continue his own training as heir, and instead ran off after his sister.
Book 3: Since their run-in with Northern Necromancers, the twins are sharing one body between them...
Marleigh's character description/notes
Hiroki aka "Hiro"
Profession: Robin Hood? (Is that a profession? We could just go "Hero" and be done with it. :) Aspect: Monkey (?)
He is the Yang twin; the energetic/impulsive man of action.
Andrea's character description/notes
Hanako aka "Hana"
Profession: Geisha/Courtesan. (Also, Seekrit weirdshit) Aspect: Phoenix
She is the Yin twin; the planner and big-picture-seer of the pair. Graceful, gracious, sociable, artistic, and ethereally lovely (though she also looks just like her twin!).