Foil
The Invisible Man
by H. G. Wells

The Invisible Man: Foil 1 key example

Chapter 23: In Drury Lane
Explanation and Analysis—Griffin and Doctor Kemp:

Griffin and Dr. Kemp, due to their similar backgrounds but opposite natures, are foils for each other. They are both brilliant scientists, as Griffin turns himself invisible and Dr. Kemp is a well-respected physician who is devoted to his work. They both went to the same university and had an acquaintanceship.