He appears to be made of metal and doll parts. He has a mustache and a crew cut, a large chin and a pipe made of what appears to be a toothpick and a cork sticking out of his mouth, a metallic body that looks like an engine, a spring attached to a plastic muscled arm, a rod with a hook arm, another spring attached to a peg leg and a blue and white striped leg with a boot.
Sean Brawn considers himself to be a great hero, similar to Avalon Centrifuge. However, unlike Avalon, who's ego is somewhat justified by his inventions, Sean Brawn only ever gets into trouble and messes things up, annoying The MegaBrain to no end.
His surname, Brawn could refer to physical strength. Brawn may also refer to a type of jellied meat, however it is most likely the former.