Warning! Spoilers ahead for Young Sheldon season 6 episode 7.
Missy became much like The Big Bang Theory's Penny on Young Sheldon season 6. Sheldon's twin sister was barely on The Big Bang Theory but became an immediate fan-favorite thanks to her personality which cannot be more different than her brother's. In the brief time she spent time in Pasadena, she struck a quick friendship with Penny, who fended off the boys from trying to hit on her ruthlessly. Looking back, their immediate adoration of each other shouldn't have been surprising considering their similarities as seen on Young Sheldon.
CBS leans into this idea in Young Sheldon season 6, episode 7 where Missy wears a Wonder Woman shirt while working at the comic shop. After Mary and George lost their full-time jobs, the Cooper twins found ways to help with their financial situation, resulting in Missy nabbing a part-time job. Several years earlier, The Big Bang Theory featured its most prominent reference to Diane Prince when Penny dressed up as Wonder Woman for Halloween. This suggests that the DC heroine resonated with both Penny and Missy, supporting the theory that his friend reminded him of his sister.
Missy Is Young Sheldon’s Version of Penny
The similarities between Missy and Leonard’s wife may also have something to do with why Sheldon was tolerant of Penny on The Big Bang Theory. Multiple times on Young Sheldon, the only Cooper daughter proves that she functions the same way Penny did on The Big Bang Theory. While they're not intellectually gifted like Sheldon, both Penny and Missy are kind, emotionally mature, and nurturing. Despite Sheldon's quirks and idiosyncrasies, they have been nothing but accommodating to him, but not to the point that they coddle him the same way Mary does. Instead, they draw some boundaries but are always understanding of him and some of his questionable choices.
Missy & Penny Would Have Been Great Friends On Big Bang Theory
Despite being one of the first Cooper family members to appear on the nerd-centric sitcom, Missy was actually barely on TBBT. Seeing how interesting her character is on Young Sheldon, it would have been better if she visited Pasadena more, or even permanently moved in with her brother. This way, CBS could have developed her friendship with Penny. This would have helped The Big Bang Theory's problematic brand of comedy, especially during its earlier seasons where they objectified and over-sexualized Penny as its only main female character. By bringing Missy into the mix, the show could have focused on a different kind of dynamic between Missy and Penny in contrast to Sheldon and his friends' bond.
It’s no secret that The Big Bang Theory’s depiction of Missy is contradictory to Young Sheldon’s version of the character. The geek-centric sitcom painted Missy as the least successful Cooper sibling in the traditional sense, which is difficult to believe considering how smart and mature she is in the prequel. Perhaps if the nerd-centric sitcom featured her more frequently, they would have been able to flesh out her character more instead of simply making her a punch line.
Young Sheldon season 6 airs Thursdays on CBS.