From Bulbapedia, the community-driven Pokémon encyclopedia.
Jovi (Japanese: マナ Mana) is the younger sister of Michael, the protagonist of Pokémon XD: Gale of Darkness, and the daughter of Lily.
In Pokémon XD: Gale of Darkness
Jovi often refers to herself in the third-person and can also be condescending towards her brother at times, such as when Michael comes to find her at Kaminko's manor and bring her back to the lab, only for Jovi to claim that Michael is the one who's lost and needs her to get back home.
In the beginning of the game, Jovi is playing hide-and-seek with a man named Adon. However, Jovi seems to forget and runs away to Dr. Kaminko's house at the beginning. After Michael defeats Chobin, he goes inside the doctor's manor and Jovi will join Michael's party.
When Michael and Jovi get back to the Pokémon Lab, Professor Krane is kidnapped. The scientists still want to build the Purify Chamber. Michael and Jovi head to Gateon Port to get a machine part.
At Gateon Port, Jovi bumps into Zook. Zook then threatens her with his Shadow Zangoose, but Mr. Verich tells one of his bodyguards to protect the girl. Ardos KOs the Zangoose with his Alakazam.
Jovi leaves after Michael returns to the Pokémon Lab with the Machine Part. She'll take it and bring it to her mom. Afterwards Jovi will stay in the lab and play with her Pokémon for the rest of the game.