Naia

 Naia and Alaric are basically the same person, and they live in the same place at the same time  without even knowing it bcuz they live in different realities. in the book every time theres a perfect 50 50 chance of something then it creates another reality.  so when naia and alaric mother was pregnant there was a perfect 50 chance it would be a girl and a 50 percent chance of it being a boy. so it split and they were both created.