On a few occasions, The Big Bang Theory could have looked very different. Mayim Bialik's character almost changed drastically on the show, with the introduction of her step-sister, who would've been played by none other than, Selena Gomez.RELATED - Mayim Bialik Picked Kevin Sussman As Her Favorite Guest Star On The Big Bang TheoryNonetheless, Bialik enjoyed a great run on the series, starting out in season 3. However, as we'll reveal, her time on the show wasn't meant for the long term.We'll take a look back at her expectations early on, and how Jim Parsons fought to keep Bialik passed season 4. Ultimately, we can safely say it all worked out for the best.

It Wasn't The First Time Big Bang Theory Almost Lost A Major Cast Member

The Big Bang Theory cast at the 2015 People's Choice Awards
via: Instar

The Big Bang Theory could've looked very different on a few occasions. According to creator Chuck Lorre, the network wasn't impressed with Kunal Nayyar following the pilot. When Lorre got off a flight, he was told Nayyar wouldn't be taking part in the meeting because he wasn't a fit for the show.

Lorre would let this stand, "When I landed in New York for the upfronts, I was informed that Kunal wasn’t there. I was like, “What do you mean he isn’t here? Why isn’t he here?”

Lorre continued, "Apparently while I was flying across the country, a CBS executive determined—unilaterally—that Kunal wasn’t right for the role and we would recast that part. Well, I did not respond well. I was furious."

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Lorre fought against the decision, mentioning that Nayyar wasn't given a fair shot and hardly had any lines during the pilot. On these grounds, Lorre wasn't ready to give up on the actor.

"I wasn’t about to recast that part because someone else made a decision. It seemed so unfair to cut the actor from the series based on what—the two lines where he whispered to Wolowitz?"

Credit to Lorre, who was right in his decision to keep Nayyar around. He played the role of Raj perfectly throughout the show's 12 seasons.

Jim Parsons Was Ready To Fight The Big Bang Theory's Creators Over Mayim Bialik's Potential Departure

At the start of Mayim Bialik's journey on The Big Bang Theory, the goal was to create a female character similar to Sheldon. However, Parsons was well aware, this type of formula was impossible to sustain long-term.

"I know at the audition they said they needed a female version of Sheldon, basically, but that's untenable long-term. There was no choice but to evolve the character."

RELATED - How Jim Parsons Really Felt About Working With Christine Baranski On The Big Bang Theory

However, during season 4, Parsons felt nervous when it came to the future of Amy's character. So much so, that he told the creators he didn't want to see Bialik's character leave the show.

"At some point in season four—I don't know if something caused it or not—I remember saying to Todd, ‘I will not let this character go without a fight."

Parsons revealed it was the first time he didn't agree with something behind the scenes.

"That was notable for me, only in that I almost never disagreed with the writers. But at some point I felt a certain way about working with Mayim that I was like, ‘If for whatever reason we seemed to be weaning her off of this show as a character, I would go and talk to them."

Parsons stood by his decision and would go on to mention that the show was made better thanks to Amy and Bernadette, as it created new storylines.

Mayim Bialik Thought She Was Done On The Big Bang Theory During Season 4

Mayim Bialik
Instar

Getting the offer as a regular on The Big Bang Theory changed Mayim Bialik's life. However, according to the actress, she felt as though things were headed in the opposite direction.

Bialik assumed her time on the show was coming to an end, and that a renewal of any sort was not in place.

"I had told my manager, 'I think this is my last episode; I think they're done with me and have done all they want to do with my character.' And that made me really sad."

"She called me back later that day and said, 'You're not going to believe what call I just got. They'd like to offer you a full position as a regular!"

Quite the turn of events for Bialik, who thrived on the show. Making her debut in season 3 back in 2010, Bialik came just short of a decade long run on the sitcom.