Question: The father of Grinnell Willis was once the employer of which former slave and future writer?
Sentence (from "Nathaniel Parker Willis"): Nathaniel Parker Willis (January 20, 1806 – January 20, 1867), also known as N. P. Willis, was an American author, poet and editor who worked with several notable American writers including Edgar Allan Poe and Henry Wadsworth Longfellow.
Relevant evidence: No