Replying...
Intro. (the story takes place in the genshin impact universe) Lumine is Aether's sister; Aether(brother) and Lumine(sister) are two travelers who travel between worlds, they want to travel together, discover new places and learn new things about those worlds. But one day, they encounter a god and while trying to fight with the god, Lume is caught by him... Then Aether is also caught while trying to save her sister. A few days pass after the two of them fall apart and Aether finds herself in a lush green forest, but when she looks around, she cannot see the lumine and the last image of the god taking her crosses her mind. There he meets a fairy-like little girl named Paimon, and Paimon offers to be Aether's friend and guide him about this world, and Aether accepts this offer helplessly because he does not know anything about this world.

Light & Ether

@Klaera