I'm not sure as you haven't provided the actual story. But usually, in a story about a pearl necklace, there could be a character who owns or desires the necklace. Maybe a wealthy lady who has the necklace as a prized possession.
There might be a thief character. Since a pearl necklace is valuable, a thief could be one of the main characters, trying to steal the necklace. This would create a lot of tension and action in the story. There could also be a detective or someone trying to protect the necklace from the thief, which would set up an interesting conflict between the two.
Another possible main character could be a jeweler. If the story focuses on the origin or authenticity of the pearl necklace, a jeweler would be an important character. The jeweler could be the one who discovers something special or suspicious about the necklace, and this discovery could be the starting point of the whole story, leading to a series of events involving other characters.
The main theme could be about greed. Often in stories involving a valuable item like a pearl necklace, characters might be consumed by greed for the wealth it represents.
The most prominent character is Mathilde Loisel. She is the one whose actions and desires drive the story. Her husband is important as he is involved in the whole situation of borrowing and then replacing the necklace. And we can't forget Madame Forestier. She is the owner of the necklace, and her wealth and the necklace itself play a big role in the plot.
Since we don't have the full story, it's hard to say exactly who the main character is. But based on the title, the main character is likely the girl who has the pearl necklace.
The main character is Kino. He is a poor pearl diver. His wife, Juana, is also an important character. And their baby, Coyotito.
The main character is a woman who borrows the necklace. There is also her husband who tries to help her when she loses the necklace.
The main characters are Madame Loisel and her husband. Madame Loisel is a discontented woman who longs for a more luxurious life. Her husband is a clerk who tries his best to please his wife but has limited means.
The main characters are the woman who borrows the necklace and her friend who lends it to her.
There might be a grizzled old sailor who has heard tales of the black pearl and is guiding the protagonist in the search. Also, perhaps a wealthy merchant who is interested in buying the pearl at any cost. The protagonist himself or herself could be a young and adventurous person, driven by curiosity or the need for wealth to find the black pearl.
There could be a brave adventurer as one of the main characters. He is the one who might be on a mission to find the black pearl.
There might be commanders as main characters too. They were in charge of the military operations at Pearl Harbor. Their decisions and actions during the chaos of the attack are part of the story. For example, they had to quickly assess the damage and figure out how to respond.