Foil - Things Learned while reading "The Hound of the Baskervilles" - Sherlock Holmes

Image via Wikipedia Don Quixote and his sidekick Sancho Panza, by Gustave Doré: their character contrasts are made manifest not only by their behavior, but also by their physical appearance.

"I feel a foil as quick and supple as my own. "

Foil (literature) - Wikipedia, the free encyclopedia: "In fiction, a foil is a character who contrasts with another character (usually the protagonist) in order to highlight various features of that other character's personality, throwing these characteristics into sharper focus."