Agnes apparently comes from the fallen nation of Khaenri'ah. How that can be is unknown, as the nation fell 500 years ago. She may simply be descended from a survivor, or maybe there's some power keeping her alive. It's also possible that she's simply not human, but there's no signs of that being the case, from what has been seen of her thus far.
Height: Stand-in (if needed, she's no taller than 5' 4")
Weight: ???
Age: ??? (At least 550, likely far older)
Place of Birth: ???
Homeland: Khaenri'ah