Final answer:
The protagonist is the main character in a story who embodies more complexity than solely being good or a hero, as exemplified by Satan in 'Paradise Lost.' Stories also include secondary characters who can support or oppose the main characters. The antagonist acts as the main character's chief nemesis and is essential for creating narrative conflict.
Step-by-step explanation:
The protagonist is the main character of a story, which is often, but not always synonymous with being the 'hero.' Although protagonists often represent the moral values of the society depicted in the narrative, they have more moral ambiguity than that, and they are not always 'good.' An example of such complexity is the character of Satan in John Milton's 'Paradise Lost,' who is the protagonist but certainly not considered a hero in the traditional sense.
In addition to the protagonist and antagonist, stories typically have a cast of secondary or minor characters. These characters can support or oppose the main characters, and they are fleshed out through descriptions, interactions, and dialogue. The physical appearance, thoughts, feelings, and actions of these characters contribute to the richness of the narrative.
The antagonist, often called a 'villain,' is the chief nemesis of the protagonist and creates conflict within the story. The relationship between the protagonist and antagonist, as well as their individual characteristics, drives the plot forward and engages readers with the struggles within the narrative.