Luna Belle Henderson is the daughter of Zs'Skayr/Ghostfreak (Ben 10 series) and Giegue/Giygas (Mother/EarthBound games). This makes her a half-sister to Kimiko, Konrad and the Serket twins, Faeton and Anurto. She is also the adoptive sister of Sanjay.
Luna was born some time after Zs'Skayr got into a horrible fight with Giegue, which ended in him being raped (he was weakened after his powers became neutralized). After her birth, Zs'Skayr ordered that Vriska kill her shortly before passing out. As strange as it was for her, Vriska found herself unable to kill her after being caught in the act by a tearful Faeton and Anurto, who wondered what she was doing to their little sister. Before appearifying Luna to Earth, she told them to take a good long look at her, because odds are, they wouldn't see her again and that it was all for the best. Zs'Skayr to this day has no idea that his youngest daughter is still alive.
She has been adopted by a human family.
(To be edited later.)
In general, Luna is cheerful and easily excited over the littlest of things. However, she does not tend to get in trouble, and always obeys her superiors. But under that bright personality, Luna is extremely sensitive, and gets sad very easily.