The House of Dies Drear
Mr. Carr lives on land connected to both the Drear land, and the Darrow land. He was friends with Wilbur Darrow (one of Mac's brothers), but River Swift (the grandfather) didn't want him around, he says, because he's white. Mr. Carr is the one who calls Mayhew to let him know Mr. Pluto is sick and that the Darrows are terrorizing him. He makes sure Mr. Small understands that he and his brothers want to be friends with them. The Smalls can count on him if they need anything.