Fans of The Big Bang Theory will know that Kaley Cuoco’s Penny was a very important part of the series since its very first episode, though looking back, co-creator Chuck Lorre feels that it took some time for the writers to really figure out how best to use the character for the show.

On March 17, The Official Big Bang Theory Podcast was launched, kicking off what will be a companion podcast for every episode of the hit sitcom. The first episode featured Lorre as a special guest alongside former Warner Bros. Television Group chairman Peter Roth, who joined host Jessica Radloff to discuss the original unaired pilot. One major difference with that pilot is that Cuoco hadn’t yet been cast, with two other female characters featured with Johnny Galecki’s Leonard Hofstadter and Jim Parsons’ Sheldon Cooper. The plans were changed to have Penny replace the two women, and the way Cuoco played her helped make the character more relatable for viewers.

“They could be as obnoxious, or for Sheldon, as off-putting as possible, but you forgave them because there was this kind of childish naivete,” Lorre explained (via People). “The magic of Kaley was, Kaley’s character — as we figured this thing out on the fly — was amused by them, was not critical. If she got angry, it wasn’t harsh. The audience responded to that.”

Roth added, “[Penny] 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.”