What does the term 'evil twin' trope refer to in literature?

The term 'evil twin' trope refers to a narrative device where a character has a duplicate or counterpart who embodies opposite traits. This concept is often used to explore duality within a character, highlighting contrasting traits such as good versus evil or innocence versus corruption. In literature and media, the 'evil twin' typically serves to reveal underlying aspects of the protagonist's personality or to create tension in the storyline by presenting the character's darker impulses or moral dilemmas through their alter ego. This device allows for a deeper exploration of identity and the complexities of human nature, providing a compelling dynamic in character development and plot progression.

Other choices may cover related themes, but they do not encapsulate the essence of the 'evil twin' trope as precisely. For example, while contrasting personalities are mentioned, the focus of the trope is specifically on the duality within the same character or counterpart, rather than just the existence of two contrasting personalities in a mythological context or the notion of betrayal or inner conflict represented in different ways.