Spoiler alert: This story includes details of the May 9 penultimate "Young Sheldon" episode.

You can't say you didn't see George Cooper Sr.'s death coming after seven seasons of "Young Sheldon," the prequel spinoff series to "The Big Bang Theory." After all, in the original CBS series, Sheldon Cooper (Jim Parsons) referenced his football coach father, George Sr., who died from a heart attack when the young physics genius was 14 and growing up in East Texas.

George Sr.'s death was part of the "Big Bang Theory" mythology, which was crucial to connect by the end of "Young Sheldon," which is narrated by Parsons. Still, the offscreen heart attack death of George Sr. (Lance Barber) revealed in the final moments of the May 9 episode, the last before the May 16 two-part series finale, is, well, heartbreaking.

And not just for Sheldon (Iain Armitage) and devoted TV fans.

"It was even heartbreaking for everyone on the set making that show," says "Big Bang Theory" and "Young Sheldon" co-creator and executive producer Chuck Lorre. "We're all so invested in this character. Being fictional doesn't take away the difficulty in saying goodbye. But it's been seven years in the making. We all knew this would happen."

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Here are the ramifications of George Sr.'s "Young Sheldon" death:

How did Sheldon Cooper's father die in 'Young Sheldon'?

Everything seems to be falling into place for new grandfather George Sr., suddenly sailing amid his sometimes stormy family life. His wife Mary (Zoe Perry) and daughter Missy (Raegan Revord) are even supportive of his dream job offer, coaching football at Houston's Rice University, which would require a family move.

"With the stakes so high, it makes the tragedy that unfolds an even bigger punch in the gut," says Barber.

George Sr. survives a ladder climb, fixing the roof for the house sale. His son Georgie (Montana Jordan, who will lead another spinoff series next season) admonishes him for safety reasons. The two carry away the ladder in a tender father-son moment.

But the next day, as George Sr. heads off to work, he picks up his travel mug, promises to be back for a family photo shoot and gives an unacknowledged, "See you all later." Sheldon doesn't look up from his book as his father walks out the kitchen door into the (heavenly bright) sunlight, never to return.

"It was purposely a banal nothing moment in Sheldon's life that he will struggle with," says Lorre. "Because he learns it's the last time he'll ever see his father. He will live to regret that moment in his life where he'll say, 'I could have done that better.'"

Hours later, the shocked family is informed that George Sr. died of a heart attack. Sheldon wordlessly sits with a stunned expression, processing the unfathomable loss.

Why George Sr.'s death changes his maligned 'Big Bang Theory' character

George Sr., frequently the butt of adult Sheldon's dark humor in "Big Bang," is the flawed character who changes the most due to "Young Sheldon."

"In 'Big Bang Theory,' when George was an offscreen character who's no longer alive, you could make all the jokes you want. But 'Young Sheldon' is a sweeter family show," says Steve Holland, a producer and writer on both series. "And because of Lance Barber's portrayal of George in 'Young Sheldon,' you didn't believe his dad could be that bad."

For example, adult Sheldon explains in "Big Bang Theory" that he knocks three times on a door because he traumatically walked in on his cheating father "having relations" with a mysterious blonde woman. In a March episode, the alleged infidelity is explained away in a scene where Sheldon walks in on blonde-wigged Mary role-playing with her husband as a campy German named Helga.

George Sr.'s death completes his character's redemption, explaining why Sheldon has such a dark view of his father. Sheldon is immediately consumed with grief and remorse over his final non-goodbye, which he obsesses over, starting with the last haunting stare.

"Sheldon is already playing his last moments over and over," says Barber. "All the regrets and things that he wishes he said."

What will happen in the 'Young Sheldon' finale?

The two-part May 16 finale (8 EDT/EDT) features Sheldon and his family grieving at George Sr.'s funeral.

But the finale also finds joy after loss, as Sheldon moves on to college (the California Institute of Technology, as fans already know). Parsons returns as an older Sheldon, reprising his role with Mayim Bialik, who plays his wife Amy, for the first time since "Big Bang" ended in 2019.

The screen couple has two young children. And Sheldon's struggles with fatherhood have softened his feelings about his own father, George Sr. "There's a recognition that his father is a human being who is flawed but doing the very best he can," says Lorre. "That's an epiphany you have about your parents when you're older. This finale is very much about Sheldon's perspective on his father. It changes for the better, given time and his own experience raising his children, who he doesn't understand."