A foil character is intended to:

A foil character is specifically designed to highlight differences between themselves and another character, often the protagonist. By contrasting with the main character’s traits, beliefs, or behaviors, a foil can illuminate key aspects of the main character's personality and motivations. This relationship allows the audience to better understand the complexities and nuances of the main character.

For instance, if the protagonist possesses qualities like bravery and decisiveness, a foil might be characterized by fear or indecisiveness, which serves to accentuate the protagonist's traits. This technique enriches the narrative, providing deeper insight into both characters and enhancing the overall thematic concerns of the story. The intention of using a foil is not to provide support or comic relief, nor is it to create identical characters, as those would not achieve the same effect of emphasizing contrasts and differences.