Mr. Brooke is the uncle of Dorothea and Celia. After their parents die (before the start of the novel), he's in charge of taking care of them. He's a bachelor, and has always lived by himself, so the idea of raising two girls scares him. He sends them off to be educated in Switzerland. Brooke means well, but he's kind of a doofus. He's always talking, but without saying much. Kind of like a babbling brook…maybe there's a connection with the name?