Warning! Spoilers ahead for Young Sheldon season 6, episode 19. Young Sheldon season 6, episode 19 perfectly explains Sheldon's aversion to his first The Big Bang Theory rival. As a child prodigy who grew up in Medford, Texas, and was coddled by his mother, Sheldon has been used to getting his way. He has always felt special, and the way Mary followed his every whim only worsened his sense of self-importance. However, Young Sheldon reveals that even during childhood, he suffered some setbacks and failures. While some of these experiences negatively impact his arc in The Big Bang Theory, others explain certain aspects of his story in the nerd-centric sitcom.

Young Sheldon season 6 has subjected Sheldon to some hardships in life, including the failure of his grant database. Amid all of that, the socially-inept genius is on the cusp of the next chapter of his life. Despite the CBS prequel series not making a big deal about it, Sheldon is set to graduate college from East Texas Tech before the season ends. While The Big Bang Theory has previously revealed that the future will be kind to Mary and George's son, Young Sheldon is still leaning on his concerns about what lies ahead.

Young Sheldon Explains Why He Hated Big Bang Theory's Dennis Kim So Much

In Young Sheldon season 6, episode 19, "A New Weather Girl and Stay-At-Home Coddler," Sheldon finds out that he is way behind in working on his portfolio for his post-grad aspirations. Despite being a child prodigy, he quickly realizes that getting into Caltech's physics department won't be easy. Soon, he starts to worry about falling behind in life. His conversation with Missy eventually reveals his real worry, which is that he will no longer be a young genius, but just a normal genius. This explains why he was especially threatened when he met his first The Big Bang Theory rival in season 1: Dennis Kim.

Introduced in The Big Bang Theory season 1, episode 12, "The Jerusalem Duality," Kim was a physics prodigy from North Korea and a Caltech prospect Sheldon was never good with rivals, but he didn't think of Kim as one until he mentioned that he was the youngest recipient of the prestigious Stevenson Award. While he started post-grad at 15, it was only because he lost a year after having to flee North Korea. The arrival of Kim reminded Sheldon of feeling that he was being left behind as seen in Young Sheldon season 6.

What Happened To Dennis Kim In Big Bang Theory

Unfortunately, The Big Bang Theory wasn't able to further explore the pair's relationship beyond season 1. The character only appeared in one single episode of the nerd-centric sitcom. After seeing his negative impact on Sheldon, Leonard, Howard, and Raj devised a plan to distract the North Korean prodigy, so he was no longer a threat to their friend. Ultimately, they succeeded, with Kim getting swayed by a woman. Since then, the character neither appeared nor was referenced ever again in the show. Jim Parsons' adult Sheldon narration in Young Sheldon hasn't also mentioned him.

Young Sheldon season 6 airs Thursdays on CBS.