supporting character
character in a narrative that is not focused on by the primary storyline
sidekick
subordinate but significant character in a fictional work
tritagonist
third most important character of a narrative, after the protagonist and deuteragonist
deuteragonist
second most important character in a narrative work
confidant
character in a story that a protagonist confides in and trusts
love interest
character whose main role is being the object of desire of one the main characters