Brassius is one of the Gym Leaders of the Paldea region, and is also an artist. He treats battles as an artform and tests the aesthetic sensibilities of those who challenge his Gym. He is always busy with a new project when he's not battling, inspired by his surroundings. He is best friends with Hassel, the art teacher of Naranja Academy and Paldea Elite Four member.

He has a habit of saying "avant-garde" when he sees something amazing like a piece of artwork or strong trainers.