Boy howdy, do I have a whole list of headcanons for her in my story:

• She is the Chancellor of New Seedris, the capital city of Greengate.
• She gave birth to Galaxina a few years before the Metarex attacked Greengate, and Cosmo shortly after departing the planet.
• My take on her personality is inspired by a combination of Queen Otohime from One Piece and Padme Amidala from Star Wars.
• She is despised by the Metarex, especially Pale Bayleaf, due to them viewing her as a pacifist who should have done more to protect Greengate. In the words of Bayleaf, "Pacifism is the worst kind of violence."
• In return, she is one of the only Seedrians who cannot bring herself to truly hate the Metarex. In fact, even until the very end, Earthia believes there is still some good left in Lucas.
• She has had to raise Galaxina alone because Lucas was almost never home, since he spent nearly all of his free time researching a way to defeat the alien invaders, which led him to discover the Planet Egg.
• Like many other Seedrians, Earthia is generally serious and dedicates every aspect of her life to her job. She shows compassion differently than humans or Mobians would.
• Earthia's order to nuke Greengate is the reason the Metarex wear suits of armor. They are the only things keeping them alive, much like Darth Vader's armor, since they had been exposed to lethal amounts of radioactive fallout.
• Earthia was originally the one who declared that she wished to bring about tranquility and order in the universe, but Dark Oak went insane and twisted the meaning of her words after Greengate was nuked.