Boosten is a Boo, and a partner in Paper Mario: The Thousand-Year Door 2. He lives at the Creepy Steeple. Originallly, Mario and co. had gone to where the Shadow Sirens were hiding out. In search of Vivian, they entered the Steeple. Boosten, who happened to be hiding in the room at the time, happened to overhear that Vivian couldn't come for some reason. Hearing that the world would be destroyed, he readily joined Mario's party to defend his people and his home.