Mercury is kind but gets bullied by Venus. Mercury hates being second and called small. He has a love hate relationship with the sun
Luna is more confident and is very protective of the earth. Earth is Lunas sister. Luna also hates all the other moons. But is also very insecure of their looks since theyre canonically ugly

Mercury has a crush on Luna but is too shy and scared to talk to her even though hes sarcastic. Luna doesnt really talk to Mercury but still considers him a friend
Solarballs