The Big Bang Theory co-creator Chuck Lorre has shared how Kaley Cuoco’s character was developed, saying it “took a while” to make Penny less “clichéd”.

Penny was first introduced as Leonard and Sheldon’s attractive neighbor, who lived across the hall from their apartment building. After catching Leonard’s eye, bubbly Penny quickly became a part of the geeky friend group and a firm favorite among fans.

Appearing on The Official Big Bang Theory podcast, Lorre and former Warner Bros. Television Group chairman Peter Roth reflected on the original, unaired pilot of the sitcom and discussed how Cuoco had reshaped the initially “one-dimensional” character.

“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,” Lorre told host Jessica Radloff. “We did the very clichéd—in the beginning—goofy blonde who says foolish things. It was a clichéd character, the dumb blonde. We missed it.”

“We didn’t have that right away—that what she brought to this story, to these other characters, was an intelligence that they didn’t have. A kind of intelligence that was alien to them. You know, intelligence about people and relationships and family.”

Lorre explained how Penny “brought a humanity” that was “lacking” from the socially awkward scientists. He added, “And that took a while to figure out. In the beginning, she was sadly one-dimensional in too many ways.”