The Big Bang Theory may be defying the laws of TV mechanics with its storied success, but there’s one thing co-creator Chuck Lorre said the series “missed” early on about Kaley Cuoco‘s character Penny.

In the first episode of The Official Big Bang Theory Podcast opposite former Warner Bros. Television Group chairman and CEO Peter Roth, Lorre—who also co-created Two and a Half Men — discussed the failed unaired pilot of the sitcom and being given a “do-over” following penning a “shy” script alongside collaborator Bill Prady.

The original inaugural episode featured two female main characters, Katie (Amanda Walsh) and Gilda (Iris Bahr), before Kaley Cuoco eventually stepped in as the lead following a rewrite and retaping of what would become the second and aired pilot a year later.

He added, “She was never judgmental about these characters. She was amazed by them. They brought more judgment to her than she did ever of them. And I thought that was also an important difference between the character of what Penny brought versus the character of what Katie brought in the original unaired pilot.”

Despite the dynamic element and heart Penny brought to socially inept brainiacs Sheldon Cooper (Parsons) and Leonard (Galecki), Lorre admitted that he didn’t fully grasp Penny’s complexity from the get-go.

“Even after the second pilot, we had so many episodes to go before we started to understand that there was a brilliance to Penny’s character that we had not explored,” he said, adding that early episodes depicted her as a “goofy blonde who says foolish things.”

The prolific TV writer/producer continued, “It’s a cliched character: the dumb blonde, and we missed it. We didn’t have that right away that what she brought to this story, this series, to these other characters was an intelligence that they didn’t have. A kind of intelligence that was alien to them, an intelligence about people, relationships and family.”