The protagonist is -- by definition -- the main character, whether he's the lead or not. Some definitions allow for the protagonist to be one of the main characters.
- Merriam-Webster: "the principal character in a literary work (such as a drama or story)"
- Oxford: "The basic sense of protagonist, as originally used in connection with ancient Greek drama, is ‘the main character in a play’."
- Wikipedia: "A protagonist (from Ancient Greek πρωταγωνιστής, prōtagōnistḗs, meaning 'one who plays the first part, chief actor') is the main character of a story."
The description of this trope describes a character who is not the (or a) main character. Thus, using the word "protagonist" to describe this character is incorrect.
Any suggestions for a better name for this trope?