Raj Koothrappali, played by Kunal Nayyar, became the first original cast member from The Big Bang Theory to return in the spin-off series Young Sheldon.
According to co-creator Steve Prady, the decision was driven by the story's need for a character who could perform a specific calculation, after which he is killed before using the answer.
The actor who plays Sheldon's older brother, Lance Barber, initially expressed discomfort with the plot development. By the second episode, he rationalized the multiverse concept as a justification.
Actor Kevin Sussman, who played Stuart Bloom, welcomed the reunion with Nayyar, noting their characters' shared history as single men on The Big Bang Theory.