I wonder if Sorano could be Angel of Oración Seis?
It would make sense for both her and her sister being Celestial Spirit Mages.
That short hair cut and hair band resembles Angel’s hairstyle as well.
They both have white hair and similar color schemes…
We also don’t know anything about the time before Angel was used as a slave at the Tower of Heaven when she was a child. Maybe she was abducted like this?
I don’t know, this might be a silly thought, I just thought it could be a possibility =3=