The son of Birch (originally from Johto along with Norman) and a woman native to Hoenn. Despite his father traveling across the world, Brendan has never left the small, hickish area he's from, so he has a bit of an accent and doesn't know much about larger city living, therefore romanticizing it.
While initially coming off as very abrasive and even a bit of a typical rude sexist tween to Mito when she first meets him, he was a very mild boy growing up, which got him a lot of negative attention from others. It doesn't help that he has an interest in contests, fashion, and other girly hobbies. In order to cope with being seen as pretty gay, he turned aggressive very fast after hitting puberty.
While he wants to prove himself as a good researcher and battler, he's unsure how to go about it and fails to put his full effort in, allowing Mito to consistently take the spotlight from him.
Early on into his adventure, he comes across an injured shiny Ralts, that he immediately captures and raises himself, against the advise of his father.
Through such misadventures, he learns a lot about Pokémon's individual temperaments, natures, habitats, and ways of interacting with each other and humans.