We use the terms flat and round characters to describe the depth and complexity of development of particular characters in a piece of literature. According to Britannica flat character are “two dimensional” meaning they are simple, shallow and uncomplicated and they “do not change throughout the course of a work”. They have little to no personality and lack complex emotions and motivations. They are not necessary always minor or side characters (even so they often are – see all competitors in the “The Hunger Games” aside from Katniss and arguably Peeta), they are often in the role of main character as well:
Example of a flat character (main character):
· Sherlock Holmes (His character is eccentric, however it does not really change, he already knows his truths and as a reader or watcher one only gets story about mystery solving, not specific changes Holmes’ character goes through.)
· Classic Disney princess (most of children’s stories have main character as a flat character, these stories tend to be plot driven, not focused on the arc of the character whatsoever).
Flat character are definitely not unimportant even if they are not in the role of the main protagonist. They can function as a comparison with opposites to another character/protagonist, as comic reliefs ( or antagonists (Crabbe and Boyle from “Harry Potter”).
To imagine this better, round characters on the other hand are very complex, they go through surprising development, they have depth and often internal fights that force them to change, bend and develop.
Example of a round character: Simba from “The Lion King” (He undergoes development from young and carefree to responsible and brave.)
Source: https://www.britannica.com/art/flat-character
Kateřina Brettová