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The Most Confusing Big Bang Theory Moments Explained

For 12 years, The Big Bang Theory entertained viewers with its lovable cast of nerdy scientists and their struggles to interact with the world outside of academia. What begins as a story about a physicist trying to find love with his attractive next door neighbor quickly evolves into several hilarious storylines with each character encountering unique problems with love, family, and the pursuit of happiness.

All of these storylines result in some major character arcs, and by the final episode, Sheldon, Leonard, Howard, Raj, Amy, Bernadette, and Penny all end up very different from the way they each started out at the beginning of the show. For casual viewers — and even longtime fans who see the show through reruns — this inevitably creates plenty of confusion over why their favorite characters act the way they do at different points in the series. With this in mind, here are our explanations for some of the most confusing moments in The Big Bang Theory.

Why does Leonard put up with Sheldon's annoying behavior for so many years?

Watching Sheldon Cooper torment his roommate Leonard Hofstadter may be hilarious, but actually having Sheldon as a roommate would be enough to drive anyone crazy. The "Roommate Agreement" Leonard signs in order to move in forces him to drive Sheldon everywhere and even specifies where he can stand in the bathroom. Sheldon refuses to let anyone else sit in his favorite spot on his couch. And he requires Leonard follow ridiculously specific instructions when ordering takeout.

Leonard might consider Sheldon a friend, but why would anyone want to live under those conditions? The season 2 episode "The Maternal Capacitance" offers a clue when Leonard's mother Beverly Hofstadter comes to visit and reveals she's just as strict and selfish as Sheldon. Beverly even makes Leonard prepare her tea with the same stringent requirements Sheldon demands for his takeout. This indicates Leonard was conditioned at an early age to respond submissively to unreasonable demands, showing why he lets Sheldon treat him this way

However, in later episodes, Leonard mentions he also puts up with Sheldon because the two genuinely like each other and Leonard feels Sheldon needs his help. And he's right — Sheldon may be smarter than Leonard, but he needs his roommate to navigate through social situations and stay out of trouble. It might not always be a healthy relationship, but being Sheldon's roommate means Leonard will always be needed.

Why does Amy develop such a huge crush on Penny?

When Amy Farrah Fowler first meets Penny in the episode "The Robotic Manipulation," she treats her with disdain, telling her not to use the term "Shamy" to describe her relationship with Sheldon and embarrasses Penny by openly analyzing her sex life. As time goes on, however, Amy regularly gushes over Penny's attractiveness, claims they're best friends, and infamously gives her a giant painting of the two of them together in the season 5 episode "The Rothman Disintegration."

Considering how condescending Amy was toward Penny initially, her "girl crush" seems to come out of nowhere. Some viewers speculate this means Amy has bisexual tendencies, Admittedly, Amy has given some indications of this, especially when she mentions an earlier version of the Penny/Amy painting was done with both of them in the nude.

However, as Amy reveals more about her background, fans learn she was a very lonely person who never had any friends from nursery school all the way through graduate school. When she finally receives a chance to become one of the "cool kids" by joining Penny's group, her desire for friends, coupled with her social awkwardness, likely makes her take things a step too far.

Why does Sheldon offer to have sex with Amy?

Sheldon and Amy's love life (or lack thereof) is a constant source of humor in the early years of their relationship. Although Amy indicates she wants to have a physical relationship with Sheldon, her apparently asexual boyfriend insists he is uninterested in having "coitus." So, it comes as a major surprise in season 9 when Sheldon offers to have sex with Amy on her birthday in "The Opening Night Excitation." Sheldon even gives up seeing the premiere of The Force Awakens to spend the night with Amy, marking a major shift in his character.

For "Shamy" fans, however, this was a long moment coming. The show regularly offers scenes revealing Sheldon is capable of intimacy — he just needs more time to become comfortable with the idea. Earlier episodes show Sheldon slowly adjusting to holding hands with Amy and cuddling. When she kisses him in "The Agreement Dissection," he regards the experience as "fascinating" and later initiates kisses himself.

However, the best piece of foreshadowing happens in the season 6 episode "The Cooper/Kripke Inversion." Asked point blank by Penny if he will ever sleep with Amy, Sheldon admits he's grown comfortable enough with his girlfriend to the point where a physical encounter is "a possibility." Judging by the look on Amy's face at the end of their night together, the experience was definitely worth the wait.

Why does Bernadette develop such a mean streak?

When Howard Wolowitz begins dating microbiologist Bernadette Rostenkowski, she seems like a very sweet girl. With her high-pitched voice, petite stature, and nerdy glasses, Bernadette appears the perfect picture of a demure, kind-hearted girlfriend.

However, fans soon learn Bernadette has plenty of negative qualities. She's fiercely competitive in games and verbally abuses Leonard when they are paired together for a scavenger hunt to make him work faster. She emasculates Howard by reminding him she makes more money than he does. And she's such a bully in her workplace that her co-workers give her a handicapped washroom as a personal bathroom just to avoid upsetting her.

To explain these seemingly contradictory personality traits, multiple episodes reveal Bernadette has a major complex about her height and feels she isn't taken seriously due to her waifish appearance. As a result, she adopts an overly aggressive attitude to get her way. Unfortunately, Bernadette enjoys getting her way so much that she regularly intimidates, lies to, and manipulates others, making her one of the meaner characters on the show.

Why doesn't Howard have a PhD?

Unlike most of the other characters on the show, Howard doesn't have a PhD. As a graduate of MIT, Howard has a Master's degree which helped him become an aerospace engineer at Caltech's Department of Applied Physics. Since engineers don't need doctorates like physicists, Howard doesn't have any real reason to go further in his education.

Unfortunately, Howard's lack of a PhD makes him a constant target of ridicule by Sheldon, who regards him as less educated than (and therefore not as smart as) his friends. Howard usually points out that, as an engineer, he gets to build the machines that his friends can only theorize about. His engineering expertise even allows him to visit the International Space Station as a Payload Specialist in season 5.

Even so, the ridicule over his lack of a PhD does get to him and in the season 8 episode "The Junior Professor Solution," Howard takes a graduate course with Sheldon to start earning his PhD (only to stop when he discovers he can't stand Sheldon's insulting teaching methods). Notably, Howard is already smart enough to answer doctorate-level questions correctly and likely only wants a PhD due to the insecurity he feels being surrounded by (and married to) people with doctorates.

Why does Raj sabotage so many of his relationships?

While Leonard, Howard, and Sheldon are all awkward around women, Rajesh "Raj" Koothrappali takes social awkwardness to a whole new level. In early seasons, Raj becomes mute around females and has to consume alcohol just to talk to women. However, this leads to more problems as "drunk Raj" can be more obnoxious and overbearing than his ordinary self.

By season 6, Raj gets into a relationship with Lucy, an equally socially awkward woman, and gains the ability to speak to girls while sober. While this allows Raj to finally have a serious relationship, he continues to fail at most of his other relationships. In the final season, Raj decides to go through with an arranged marriage to a woman named Anu, but even this falls apart, leaving Raj the only unmarried member of the group at the end of the show.

Although this seems unfair, Raj has always had high standards for his relationships. A fan of romantic movies, Raj yearns to have an unrealistic romance like the ones portrayed in Notting Hill or The Princess Bride. This causes him to abandon good relationships in favor of something better, as he does in season 9 when he breaks up with his girlfriend Emily Sweeney to pursue a woman he just met (they later break up). Despite this, Raj realizes at the end of the show that he's surrounded by friends who love him, particularly Howard, who believes Raj will eventually discover a compatible woman.

How did Stuart manage to get into a long-term relationship?

Comic shop owner Stuart Bloom goes through a major personality change early in the show. In season 2, Stuart suavely asks Penny out on a date and actually shows her a good time. Shortly after, however, he becomes insecure, depressed, and unsuccessful with women — traits that largely define his character for the remainder of the show. At one point, it seems like the only positive relationship with a woman Stuart has is with Howard's overweight and unseen mother Debbie Wolowitz, whom he cares for until she passes away in season 8.

However, by season 11, Howard hires an attractive co-manager, Denise, who finds him "hot" after he answers several Star Wars trivia questions accurately during Sheldon and Amy's wedding. The two begin dating and enter into a long-term relationship that even Stuart's remaining insecurities can't ruin.

While her time on the show is brief, Denise represents a largely unacknowledged demographic on The Big Bang Theory — female comic book fans. As someone who shares Stuart's love for pop culture and superheroes, she validates his passions and helps him be comfortable with himself. Although a throwaway joke in "The Citation Negation" suggests she's attracted to Stuart's unhealthy physique because her parents owned a funeral home, it's more likely their relationship succeeds because their personalities complement each other.

Why is Penny suddenly okay with becoming a mother?

After marrying Leonard, Penny confesses she has no desire to be a mother. This leads to some friction with her husband, and Leonard even considers donating his sperm to another couple just so he can father a child. Eventually, he accepts he doesn't want a child he can't raise and chooses to be content with the life he's building with Penny.

However, in the series finale, Penny reveals she's pregnant — and is now apparently excited about becoming a mother. In a Hollywood Reporter interview, executive producer Steve Molaro indicated that Penny's pregnancy is a reference to a line from the pilot episode when Leonard states their babies will be "smart and beautiful." Since this only takes Leonard's feelings into account, Penny's sudden desire for motherhood seems out of character.

While it's possible that Penny has changed her perspective on having kids after becoming pregnant, it's also likely that she hasn't fully processed her new situation. In her final scene, Penny informs Sheldon that she hasn't told her parents about her pregnancy yet, suggesting she isn't completely comfortable with the idea of parenthood. This could lead to further drama, but the series ends before it can be explored.

How did Howard become such a devoted father and husband?

Of all the character arcs on The Big Bang Theory, Howard's journey is arguably the most extreme. When viewers first meet him in season 1, Howard comes across as a lecherous womanizer who creeps girls out. Yet by the end of the series, he's in a stable marriage with Bernadette and the devoted father of two children.

While it might seem like Howard has become a completely different person, several episodes help reveal what motivated this change. In season 5, Howard explains that due to his father abandoning him at a young age, he wants to have kids and offer them the childhood he never had. This desire may have fueled his overzealous attempts to find a girlfriend, but without a positive male role model in his life, he came on too strong and failed at many early relationships.

In the season 5 episode "The Stag Convergence," Howard confesses he's disgusted by his past behavior and has stopped being his lecherous self because of his relationship with Bernadette. While he continues to engage in goofy antics, his behavior from that point on is more mature, indicating Bernadette provides him with the incentive to be the husband and father he wants to be.

Why did it take so long for the elevator to be fixed?

From the beginning of the series, the elevator in Sheldon, Leonard, and Penny's apartment is out of order. This forces the characters to walk up the stairs in almost every episode, allowing them to have exposition-laden conversations. While this is a fun running gag, it does beg the question — how could any apartment building manage to have an inoperative elevator so long without violating some building code?

Different episodes offer different explanations for how long the elevator has been broken. In season 3, Leonard claims the elevator broke in 2003 after Sheldon threw a volatile rocket fuel formula into it, saving Leonard's life, although in season 1, he claims the elevator broke in 2006. In the final season episode "The Change Constant," the elevator is fixed — 16 years after it first broke.

As it seems ridiculous that the building's landlord received no complaints for 16 years (or was somehow able to avoid any legal reprisals for negligence), this is one plot hole that doesn't have an easy explanation. Perhaps the building is full of tenants that don't mind the extra exercise of climbing up and down stairs, but even for a sitcom, that seems like a stretch.