https://hellogiggles.com/wcw-bernadette-big-bang-theory/

There’s a reason The Big Bang Theory is among the highest-rated and most-watched comedies in America. For starters, its four main guy characters are hilarious to watch, because they somehow continue to be awkward even in the show’s current season-almost nine years after its premiere. Sure, they’ve grown up a bit-Raj can talk to girls without alcohol now, Howard is married and has been to space, Leonard finally got the girl, and Sheldon even lost his V-card. But even though the guys are fun to watch, the real heart of the series is in the female characters. Penny, Amy, and Bernadette are the epitome of friendship goals because despite their difference in personality, they’re always there for each

https://hellogiggles.com/wcw-bernadette-big-bang-theory/
It's hard to believe Amy and Bernadette weren't there from the beginning looking back these days. They really are now indispensable characters in the show. It's hard for sitcoms to succeed with additions to a cast in later season, but Big Bang succeeded with those two.