Young Sheldon's upcoming season 4 premiere will feature a continuation of a The Big Bang Theory storyline. Young Sheldon is a spinoff of the smash CBS comedy, which finished its run last year. The Big Bang Theory is considered one of the most popular shows of the decade and was a star performer for the network throughout its run. Young Sheldon focuses on Jim Parsons' character as he grows up in Texas. It mainly centers around his attempts to fit in at school and with his family, though he doesn't feel he has much in common with them thanks to his intellect.
Throughout its run, Young Sheldon has often referenced The Big Bang Theory. Parsons provides the voice of adult Sheldon and is also an executive producer on the prequel series. Additionally, Bob Newhart has guest-starred on both shows as Professor Proton, a TV scientist and favorite of Sheldon's. Notably, Kaley Cuoco, who played Penny on The Big Bang Theory, provided a voice cameo in season 3 of Young Sheldon, though not as her original character. However, Young Sheldon's season 2 finale arguably showed the biggest connection to the flagship show. As it aired the same night as The Big Bang Theory's series finale, it mentioned the Nobel Prize and also showed the original series' cast as children.
Speaking with TVLine, Young Sheldon co-creator Steve Molaro revealed fans of the original show are in for a treat in the season 4 premiere, which airs this week. Molaro stated it has to do with Parsons' role specifically, saying, “Adult Sheldon is not alone in his narration at the end of the episode. It’s a fun, unexpected continuation of the Big Bang Theory storyline.”
It's hard to say for sure who will join Parsons in the premiere episode. The Big Bang Theory didn't utilize narration, so there are no clues to be garnered from that. However, it's worth noting it would be much easier for a core cast member from the original show to pop by via voiceover than in person. Not only is it hard to feature a character from The Big Bang Theory because of when Young Sheldon takes place, but also because shows are trying to limit guest-stars right now due to the coronavirus pandemic. In contrast, it would be relatively simple for someone from The Big Bang Theory to do voiceover work from home.
The use of the word "storyline" is also curious. It seems more likely a Big Bang Theory character will join adult Sheldon for some sort of reference or joke from the original show. Hopefully, as Molaro indicated, it will serve as a fun moment for viewers of both The Big Bang Theory and Young Sheldon. Audiences will find out for sure when Young Sheldon season 4 begins on Thursday.
Source: TVLine