Foil
A dramatic character who enhances or deflates another character by contrast. Based on the literal jeweler’s foil, or black velvet cloth held behind a piece of jewelry to allow it to shine in contrast. Horatio, in Shakespeare’s Hamlet, represents the definitive foil to Hamlet. [1] is a character who is different from another character and the foil character's difference highlights the qualities of the other character, which most of the time is the [2]. Another way to interpret a foil character would be to explain them as a [3] with a contrasting personality.