. Warning! Spoilers ahead for Young Sheldon season 5, episode 13.
Missy (Raegan Revord) ends up being the least successful Cooper sibling and Young Sheldon just explained why. Typically centered on its titular character, The Big Bang Theory spin-off has also dedicated a considerable amount of screen time to Sheldon's (Iain Armitage) family. That includes her twin sister, Missy, who viewers previously knew as an adult after appearing in the original series.
Sheldon's mother, Mary (Laurie Metcalf), was the first person from the Cooper clan to make a cameo on The Big Bang Theory. After she visited her son, Missy followed, and the fact that she's more sociable compared to the socially-inept genius surprised the Pasadena gang. It would then be another decade before Missy returned to California for Sheldon's wedding to Amy (Mayim Bialik) in The Big Bang Theory season 11. That was the last time she physically appeared in the show, even as her twin won the Nobel Prize in the finale, but the nerd-centric show at least revealed more about her, including how her life was going as an adult.
While Sheldon excelled as a physicist and Georgie (Montana Jordan) built his business, Missy spent her time in a miserable marriage. As revealed in her last appearance on The Big Bang Theory, Missy was expecting but was also separated from her husband, who could be Billy (Wyatt McClure) and other than that, she had nothing else going on for herself. This is despite her clearly having her own attributes; as seen in Young Sheldon, she has street smarts, she's sassy and charming and frankly, she could've done whatever she wanted professionally, and there's a good chance that she would've succeeded. Unfortunately, the difference between her and her brothers is that she allows other people's opinions to influence her. In Young Sheldon season 5, episode 13, "A Lot of Band-Aids and the Cooper Surrender," Missy ended up facing a lot of problems because she wanted to please her friends, suggesting this could well have been a problem that carried into later life.
The course of events all started when Missy got in another conflict with Mary (Zoe Perry) after she insisted on getting a red skirt because all her friends had the same item of clothing. The Cooper matriarch refused to buy it because she felt it was too short, and also because it wasn't allowed in accordance with her school's dress code. It wasn't until Meemaw (Annie Potts) stepped in and paid for it that the pair stopped arguing. However, her friends noticed that she didn't shave her legs and mocked her - so she then shaved, but since she didn't know how to do it properly, she ended up having a lot of cuts. Basically, all her effort to get on her peers' good side backfired. Not only was she humiliated by them, but she also ended up injured as an added insult. This wasn't the first time that Sheldon’s twin proved how important her friends' opinions were in Young Sheldon season 5. Earlier the ongoing year, Missy lashed out at George (Lance Barber) for allowing Billy to court her and Mary for staging sex talk at school. Both instances led her schoolmates to tease her.
Although Missy didn't end up with a successful professional life like her brothers, Young Sheldon previously revealed that she ends up having a great life. After her final appearance on The Big Bang Theory, she ultimately gets a loving family after her separation from her first husband. As the prequel spin-off continues, it will be interesting to see if more information about her future will be revealed moving forward.
Young Sheldon airs every Thursday on CBS.