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The Big Bang Theory Storylines That Disappeared Without Explanation

"The Big Bang Theory," which ran 2007-2019, was a ratings juggernaut like few others for CBS. Naturally the company wanted to milk the popularity of the series for all its worth. That was why we got 12 seasons of "The Big Bang Theory" spanning more than a decade, with an additional spinoff prequel series to boot.  

Over the course of the 12 seasons, audiences watched shy, nerdy scientist Leonard Hofstadter (Johnny Galecki) try to woo the pretty girl next door Penny (Kaley Cuoco) in spite of his best friends Sheldon Cooper (Jim Parsons), Howard Wolowitz (Simon Helberg) and Rajesh Koothrappali (Kunal Nayyar) dragging him down with their combined geekiness and social awkwardness. Eventually Leonard manages to ask Penny out, only to discover the course of true love never runs smooth, as the two kept breaking up and getting back together. In later seasons, the main cast grew to include Howard's paramour Bernadette Rostenkowski (Melissa Rauch) and Sheldon's eventual wife Amy Farrah Fowler (Mayim Bialik). 

With a large central cast and many recurring characters, there were certain storylines that "The Big Bang Theory" introduced over the years, only to drop them abruptly and without explanation. Here are some such aborted storylines that left fans scratching their heads.  

What happened to the Time Machine?

The central conflict of the early seasons of "The Big Bang Theory" revolved around Leonard's struggles to balance his geeky, child-like interests with his desire to appear like a mature adult whom Penny might date. One of the best depictions of this conflict occurs in "The Nerdvana Annihilation" (Season 1, Episode 14).  

Leonard accidentally buys a life-sized replica of a time machine from a famous movie, which kicks off a series of events ending with Penny angrily calling Leonard out for his childish hobbies. While Leonard decides to become more grown-up, his friends are thrilled to have the time machine, and fight over who gets to store the very large contraption in their residence. 

As a compromise, the friends decide to take turns keeping the machine at their home for equal amounts of time. By the end of the episode, Leonard had gone back to being his geeky self, and we see Sheldon still playing with the time machine. But the device was never mentioned or seen again after the episode. Considering its size and the love the four friends had for it, you would think it would show up in the background or be referenced in some manner in later episodes.   

Where did Issabella go?

While all four main guys on "The Big Bang Theory" have trouble attracting women, Raj is the one who seems to be actively repelling them most of the time. Since he's extremely shy and lacking in self-confidence, Raj does not go on many dates, and it is a major event whenever he does manage to get a women interested in him.

One such woman was Issabella María Concepción (Maria Canals-Barrera), who worked at the same University as Raj. The two had an interesting meet-cute in "The Brain Bowl Incubation" (Season 10, Episode 8) that explored their different stations in life, since Raj was an astrophysicist while Issabella was a cleaning lady with a grown-up son. After a couple of false starts, the two set up a date by the end of the episode. Raj is, understandably, excited.

And yet, we never get to see Issabella again, aside from a brief mention that she and Raj broke up in a later episode — without an explanation being provided. Considering how well the two hit it off in their brief time together, it would have been nice to have Issabella around a bit longer, and see Raj be the grown-up for change while dealing with her 19-year-old son.

What happened to Cinnamon?

It says much about the pathetic state of Raj's romantic life that the healthiest and most fulfilling relationship he ever developed on the show was with his dog Cinnamon. The tiny Yorkshire Terrier was the light of Raj's life, and he spoiled her rotten with frequent treats, an extravagant lifestyle, and all the pent-up love and affection that Raj so desperately wanted to shower on a girlfriend.

In fact, Howard made an entire game called "Emily or Cinnamon" to poke fun at the fact that Raj talked to his dog like it were his girlfriend. All in all, Cinnamon was a welcome addition to Raj's life as well as the show, since it gave the character something to do when the other guys were busy attending to their duties as boyfriends. 

And then suddenly Cinnamon stopped showing up in any major capacity. The long-running narrative arc of Raj forming an unhealthy attachment to his dog and using it to replace the missing romance from his life was dropped. Cinnamon was then only seen in the background a few times or mentioned in passing by Raj.   

Did Penny ever graduate and become an entrepreneur?

"The Big Bang Theory" always took great pains to emphasize how Penny was intellectually inferior to the four main guys. She frequently needed their help with technical devices, often could not make heads or tails of what Sheldon was talking about, and took little interest in subjects outside her sphere of work. This has only fed into the viewpoint of critics who accuse the show of being sexist

And yet Penny was occasionally seen trying to strive for something greater in her personal life — like the time she enrolled in a community college to expand her mind. The types of subjects Penny studied at college often fluctuated from history to acting to psychology. After some episodes, Penny abruptly dropped out of college for unspecified reasons and went back to being insecure about her lack of education.

Even more puzzling were Penny's occasional attempts at entrepreneurship with no follow-up. Like the time she started a business selling hair berets in "The Work Song Nanocluster" (Season 2, Episode 18). Even though she was getting huge orders big enough that she couldn't finish them in time, the business was never heard of again. Another time in "The Bus Pants Utilization" (Season 4, Episode 12), Penny was working on an app to help women shop for shoes more easily, and then the storyline was similarly never addressed again.  

Alex stopped assisting Sheldon

As "The Big Bang Theory" entered into its later seasons, the old idea of geeky, unlovable Leonard pining over Penny was starting to run out of steam. To inject fresh drama into the proceedings, the show introduced Alex (Margo Harshman), a Physics doctoral student who comes in to assist Sheldon and subsequently develops a crush on Leonard.

Alex was a welcome, level-headed addition to a cast which had grown increasingly neurotic each new season. Her crush on Leonard was also given room to breathe instead of being bundled into a single episode — from their first few conversations where Leonard made her laugh, to when Alex started hinting that she was interested in him despite the fact that he was dating Penny.  

After Alex finally asked Leonard out, Penny found out and they had a big showdown. Sheldon made things even worse by being his usual oblivious, condescending self when he showed Alex graphic images of human anatomy. That was the last major storyline that Alex was a part of in Season 6. After that her presence on the show became almost non-existent. We never got to know how she was continuing to cope with being Sheldon's assistant, and whether she tried anything else with Leonard.  

Amy had a personality makeover

When the idea was first being floated that Sheldon might get a steady girlfriend on the show, it seemed ludicrous. The character's complete disinterest in romance coupled with his general obnoxiousness that no one outside his friends circle could stand made it difficult to imagine any woman being desperate enough to go out with Sheldon.

The idea made more sense when Amy Farrah Fowler was introduced. Back then, she was basically a female version of Sheldon: An accomplished scientist who looked down on the rest of humanity and felt no hesitation in telling others how wrong they were about everything. Unfortunately, this version of Amy was proving difficult to like, or for fans to view as a long-time partner for Sheldon.

Over time the arrogant, obnoxious aspects of Amy's personality were dropped for reasons that had no in-universe explanation — but benefited the show. She became extremely needy and clingy, craving the approval of Penny and the "popular girls," and doing everything possible to fit in with the rest of the group of friends instead of believing herself to be superior to them. This new version of Amy proved a better fit for the show, since, as good as Jim Parsons was in the role, there really was no need for both a male and female version of Sheldon Cooper.    

Did Mary and Alfred get together?

Despite her brief appearances on the show, Sheldon's mom Mary Cooper (Laurie Metcalf) was one of the most dynamic characters in the series. Mary is a widow, and was often noted as a very attractive woman who received plenty of attention from Sheldon's friends, colleagues, and even his boss. 

One such character who appeared smitten with Mary was Leonard's father Alfred (Judd Hirsch). The two met in Season 9, and immediately hit it off based on their mutual dislike for Leonard's mother Beverly (Christine Baranski). Unlike the latter, Alfred was respectful of Mary's religious beliefs despite his own agnosticism. The two exhibited sparkling chemistry, to the point that Leonard and Sheldon started wondering whether they were about to become step-brothers. 

But we never got a follow-up on the Alfred/Mary pairing, other than a brief appearance they made as a couple at Sheldon's wedding. It is shown that the two spent an evening together where they talked about their situations as a widow and a divorcee. Things did not get intimate, but it was stated that the two would visit each other at their homes. Considering the difficult time they both had in their previous marriages, it is nice to imagine Alfred and Mary finding comfort in each other in their twilight years.   

Raj had a huge crush on Bernadette

Raj has had a number of hopeless crushes throughout the run of "The Big Bang Theory." But possibly the most intense crush Raj ever had was directed at Bernadette, the girlfriend of his best friend Howard. It all started when Bernadette made the mistake of being warm and sympathetic towards Raj. That was all it took for him to start crushing hard.

He proceeded to desperately pine for Bernadette, despite knowing she was with Howard. From writing such cringey lines as "Oh Bernadette, please play my clarinet," to imagining the two expressing their love for each other via a Bollywood song-and-dance number, Raj was shown to have developed feelings for Bernadette that were far more intense than usual. He even daydreamed about Howard dying and Bernadette turning to Raj for comfort in her time of grief. 

Eventually the secret of Raj's crush became public knowledge, and both Howard and Bernadette chewed Raj out for his inappropriate feelings. That was the last anyone heard of his crush on Bernadette. The two interacted frequently afterward, but Raj's romantic feelings for Bernadette were never mentioned again, and the entire storyline was essentially swept under the rug. 

Howard and his missing brother

Howard was a big mama's boy at the start of "The Big Bang Theory." His tendency and willingness to be coddled by his mother was eventually explained as a consequence of his troubled childhood: Howard's father had abandoned their family at a young age, leaving Howard and his mom to fend for themselves with and rely on each other.

Howard's feelings towards his missing father were mentioned on the show at various points. One of the biggest plot points in that direction occurred in "The Fortification Implementation" (Season 8, Episode 20). Howard discovered he had a long-lost half-brother named Josh (Matt Bennett), who showed up at Howard's doorstep one day looking to make a familial connection.

At first, Howard had no clue what to do with his unexpected family member. But by the end of the episode the two half-brothers had bonded well, and Howard was shown to be thrilled by the fact that Josh had found him. Unfortunately the character was never seen again, despite how much his presence could have helped Howard grow and mature.

The missing Meemaw

Sheldon was always the character who had the most difficulty with welcoming people into his life. But even at his asocial best, Sheldon had nothing but love for his grandmother, whom he lovingly referred to as "Meemaw." The character became famous on the show well before making an appearance because of how fondly Sheldon always spoke of her. 

Meemaw finally showed up in "The Meemaw Materialization" (Season 9, Episode 14), played by June Squibb. She was as cuddly and loving towards Sheldon as fans could have ever hoped for. Even though Meemaw started out not liking Amy, the two reached an understanding by the end of the episode based on their mutual love for Sheldon. This is why many fans were surprised when Meemaw was not present at Amy and Sheldon's wedding. 

It seemed strange that Meemaw would not be present for one of the most important days of Sheldon's life, when even his estranged brother Georgie managed to show up. Meemaw also did not make an appearance in any other episodes in the final season. 

That said, this one does have a partial explanation: Showrunner Steve Holland explained to ET that the studio did not want Squibb's portrayal of the character to take attention away from Annie Potts, who had started playing a younger and quite different version of Meemaw on "Young Sheldon" at the time. There were also plans for her to leave a voicemail that got scrapped for time.

Tam only showed up once

Before "The Big Bang Theory" even aired its final season, it had already gotten a prequel spinoff in the shape of "Young Sheldon." The latter show was set decades earlier, during Sheldon's tween years. It follows his family Texas, dealing with the fact that their son is a genius prodigy, largely uninterested in fitting in with the crowds of a pretty traditional small town.

Just like in his adult years, the younger version of Sheldon struggled to make friends with people his own age thanks to his supercilious attitude. In the early days of "Young Sheldon," the main character's only friend was Tam, a Vietnamese-American student at the same school that Sheldon attended. Tam played a major part in Sheldon's life, which naturally led to fans wondering why they had never heard Tam being so much as mentioned on "The Big Bang Theory." 

Of course, the simple answer is Tam was created specifically for "Young Sheldon" years after "The Big Bang Theory" was first conceived. Tam's absence was finally addressed on the latter show in "The Tam Turbulence" (Season 12, Episode 4). It was revealed that Sheldon was extremely hurt when Tam elected to stay back in Texas when the former moved to a different state to attend college. Although the two friends eventually reconcile, Tam doesn't appear on the show again. 

Missy and Raj could have been a thing

Even though Raj is relentlessly bad at wooing women, there had been quite a few ladies over the years who have expressed interest in him — only for him to put his foot in his mouth or find some other way to drive them away. One of the biggest missed opportunities in the romance department occurred between Raj and Sheldon's twin sister Missy (Courtney Henggeler).

She first showed up in "The Porkchop Indeterminacy" (Season 1, Episode 15). All the guys were instantly smitten with the gorgeous and charming Missy, to the extent that they had a secret competition to determine who would get to ask her out first. In the end, Leonard and Howard unsuccessfully asked her out. When Raj came to have his turn, Missy remarked that she had been hoping he would show up. Unfortunately Raj was too overcome to finish asking her out, and the matter rested there for the time. 

When Missy showed up again a decade later, Raj was excited to discover she was newly single again. Considering that he was more confident around women, it would have been a nice end to Raj's story to show him finally asking Missy out on a proper date. Unfortunately, that particular story thread was never mentioned again, and Raj ended the series as the only one without a romantic partner.   

Penny almost did not want to be a mother

Critics of "The Big Bang Theory" have often slighted the series for making Penny seem like the stereotypical "hot, dumb blonde" who is only there to get drunk, mooch off the guys, and be lusted over. Fortunately, this characterization of Penny changed over time, as she became more independent and started taking control of her life in unexpected ways. 

One such way was when Penny decided she did not want to be a mother. The subject became a serious issue in "The Procreation Calculation" (Season 12, Episode 3), to the extent that it almost threatened to derail Leonard and Penny's marriage. But the two patched up by the end of the episode and the subject was dropped in later episodes. 

Then in the series finale, it is revealed that Penny had gotten pregnant by accident after a night of drunken intimacy with Leonard. Despite her earlier objections, Penny takes the news of her pregnancy in her stride, even when other characters reminds her of her earlier insistence on never having any children. Many critics felt that Penny's sudden openness to the idea of having a kid was unearned, and undermined the previous stance the character had taken on the subject.