Erica and Jack - The adopted son and daughter of Monica and Chandler. They are born in "The Last One." It is revealed that Monica and Chandler didn't know they would be twins until they were born. Chandler suggests giving one of them up but Monica refuses, saying, "We can't split them up. They're our children and they're coming with us." Erica is named after her birth mother and Jack is named after Monica and Ross's dad Jack Geller.