Melissa "Missy" Cooper is Sheldon 's fraternal younger twin sister. She is a polar opposite in personality of her brother. She is not above physical confrontation, is very charming, and amicable , as well as possessing a very cheeky sense of humor. Missy is a main character. She is portrayed as a bratty, snarky, cynical 9-year-old who fights with Sheldon for attention from their parents.
This pushes her and Georgie closer together, whether it's helping each other with homework or trading favors. She and Sheldon shared a bedroom. However, she is shown to have a high EQ and comforts her brother often when she sees that he is feeling down.
He does the same for her. Unlike Sheldon, Missy displayed little to no interest or aptitude in schoolwork, especially math, because she found it challenging. The fact that she chose not to prioritize studying could foreshadow her ultimately having to work as a Fuddrucker's hostess for a living while both her brothers achieved middle to upper-class standing as a physicist Sheldon and tire entrepreneur George Jr. Missy has a sweet tooth for candy. Her parents spoiled her on a daily basis by buying her sweets and letting her watch TV all day long, but she is incredibly clever like her brothers when she wants to get her way.
The methods she uses often provides comic relief. The series starts out with the family eating dinner and having a good time. Missy is forced to go to church with Sheldon and Mary. She talks to Sheldon at service, prompting a woman to tell them to stay quiet. At night, she blames Sheldon for causing the parents to argue again; he rebuffs that argument saying it is about money.
The next day at the kitchen table, she tells Georgie that Sheldon could be in a special class and people will make fun of him. Pilot Young Sheldon. Missy is working at the kitchen table, and Georgie comes home, and she comments that Sheldon has no friends. That night, when Sheldon says that the book he had been reading about making friends was proving inconclusive, she tells Sheldon the the checkout list in the back is a list of people who want to make friends.
