Aether and Lumine have been traveling worlds for an eternity searching for something sent from their mother, a home, the time they came back, their mother was long gone, their father comforted them but they refused to believe that she was gone. So they continued their journey, hoping to seek their mother in another world, they believed their father was wrong, they were determined to find their mother. But then They lost all hope and decided to head back. But soon an unknown god stopped them from moving from world to world. Causing them to get separated in the planet, called, Teyvat.