Latias and her brother, Latios, lived in the Secret Garden in Alto Mare, where they were the guardians of the Soul Dew. They were friends with Lorenzo and Bianca.
Latias and Latios presented some very unique powers in the movie, such as sight-sharing, invisibility and shapeshifting. Latias commonly shapeshifts to appear the same as Bianca, and befriended Ash under her persona. She may have a crush on him as well, as was hinted in the movie, undoubtedly because he saved her from Annie and Oakley.
Ash and Latias
Latias is a very docile Pokémon. She appeared to dislike fighting and was easily scared off by any conflict or anything attempting to cause harm to her. She cared much for people and Pokémon close to her, including Ash, Latios, Bianca and Lorenzo.