Bernadette is one of the main characters on the show, even though she was not in the beginning. She’s introduced as one of Penny’s co-workers at the Cheesecake Factory.
Her main purpose was to serve as the romantic interest of Howard Wolowitz. All things said, he really didn’t deserve her, at least at first.
But she has the (not so bright) idea to marry him but luckily for her, he ends up being a pretty faithful husband.
The two of them have two kids together and they live a pretty normal life as parents.
But overall, out of the main characters, I would say she’s probably my least favorite. Just because she’s not exactly super interesting. She’s got a lot of fire in her personality when she’s angry but that’s about it outside of the wife and mother character that she is.