Prickly, pedantic, humorless, narcissistic, and helpless in the face of many commonplace tasks: Dr. Sheldon Cooper beginsThe Big Bang Theorywith many a mark against him. Yet it is these very qualities that make him so endearing a character, so singular a presence on the silver screen, and without those crushing limitations, he would have nowhere to grow.

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Sheldon sits in the passenger’s seat while Leonard drives in The Big Bang Theory

Though his stubbornness can often seem an immovable object, it is pushed throughout the series by an unstoppable force: friendship. Sheldon may not wish to change or even see the need to, but change he does, and almost every time it happens it is because his friends fought to bring forth a better Sheldon, like sculptors coaxing a statue out of marble.

10Sheldon Drives

Who will drive Sheldon to the comic book store, the train store, Caltech, or on any number of disagreeable errands? This question looms over many episodes early inThe Big Bang Theory,because Sheldon doesn’t drive.

His incessant badgering of his friends, in particular Leonard, to drive him to and fro is a free joke generator,andthings only get funnierwhen the truth about his unwillingness to drive comes out. Sheldon receiving his license represents increased independence and a step out of his permanent childhood, though it means no more “airbag” pillows to the face during driving simulations.

Wil Wheaton talks on the phone in The Big Bang Theory

9Sheldon Makes New Friends

Early on, Sheldon’s only friends are Leonard, Howard, and Raj, and if pressed Sheldon would likely say that Howard and Raj are expendable. Yet due to Leonard’s nagging influence and, more importantly, Penny’s attempts to loosen Sheldon up, Sheldon slowly and begrudgingly makes other friends.

Amy, Bernadette, Stuart, and even former nemesis Wil Wheaton all enter his social orbit, and though these friendships are burdened by near-constant gaffes and insults from a man oblivious to the needs of others, they are friendships that outlast every storm. Sheldon’s new sociability might have beenmet with mixed reviews,but it grew the character like little else.

Sheldon and Amy work together in Amy’s lab in The Big Bang Theory

8Sheldon Respects The Other Sciences

Sheldon looks down on geology, biology, and virtually every scholastic subject except physics, because in his mind only theoretical physics is “real” science.His ego clings to this view of physics for a long time.

At last, however, learning more about the work of microbiologist Bernadette, neurobiologist Amy, and even geologist Bert taught Sheldon that while he may love physics most, the other subjects are not without their merits, nor are the scientists who have devoted their lives to their study. Sheldon might appreciate geology little more than he doesPenny’s stylish wardrobe,but at least now there is a layer of respect beneath his jabs.

A close-up of Sheldon’s favorite spot on the couch in The Big Bang Theory

7Sheldon Moves Out

The apartment he shares with Leonard is precious to Sheldon. At least, his spot on the couch is precious to him. The running joke of Sheldon’s spot could’ve carriedany great comedy.Other than the train store and Stuart’s comic book shop, there are few places where Sheldon feels comfortable, and none more so than in his apartment.

Leonard, Penny, and Amy scarcely dream that Sheldon will feel comfortable living elsewhere,and yet with time, gentle persuasion, and a bit of deception, they eventually wear him down, and in the end, Sheldon is happy they did. Moving away from Leonard, even if it is just across the hall, in some ways marks the last great step towards maturity for Sheldon, which may be why he resented it so much.

Leonard and Penny both reach for a wine glass in The Big Bang Theory

6Sheldon Loosens Up About Rules

Sheldon is most comfortable when dictating every last detail of his life with a dictator’s iron fist, hence “the Roommate Agreement”: half-legalese, half-neurosis, 100% the bane of Leonard’s existence. Whistling in the apartment is forbidden.

One must stand only so close to the mirror when brushing one’s teeth. Bathroom time is scheduled. It’s enough fodder fora comedy special.Of all the changes that Sheldon undergoes, hisloosening up about rules might be the greatest gift to those around him,in particular Leonard, who for years suffered through Sheldon at his most nitpicky and pedantic. Though Sheldon never becomes the spontaneous spirit that Howard is, he does relax.

Raj, Leonard, Howard, and Sheldon sit on the couch with beards in The Big Bang Theory

5Sheldon Switches To Dark Matter

Before Sheldon loved Amy Farrah-Fowler he loved string theory. His obsession with the subject is so absolute that everyone, including him, is convinced that he will likely one day win a Pulitzer for his research. No one is more surprised or upset than Sheldon himself when stagnant research forces him to shift his professional trajectory to dark matter, jeopardizing everything he’s worked for since childhood.

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Though the shift is dramatic and the consequences are at first severe,opening his eyes to new possibilities turns out to be exactly the kind of shakeup Sheldon needs, and by turning toward new scientific horizons, Sheldon is able to make the scientific leap that he had only dreamed of with string theory.

4Sheldon Develops A Sense Of Humor

It is not a coincidence that Sheldon adores Spock. To him, the Vulcans are the embodiment of scientific detachment: dispassionate, objective, and humorless. During Leonard’s interview as a prospective roommate, Leonard cracks a joke, and Sheldon marks it down as a strike against him.

Then came the Age of Bazinga,when the badgering of his friends wore away his stoic exterior, and the jokes and pranks flooded forth. Sheldon’s humor might be too dry, arch, or gently scolding for some, and might not matchSeinfeld’sbest humor,but he proves himself to be a wellspring for comedy, even intentional comedy, once he’s set his mind to being funny.

Howard, Sheldon, and Raj share a Vulcan gesture in The Big Bang Theory

3Sheldon Appreciates His Friends

Leonard, Howard, Raj, and Penny bring much to Sheldon’s life. Even the couch and therefore Sheldon’s precious “spot” only exist because Leonard purchased it, yet early in the series Sheldon is oblivious to the constant, giving gestures and support of his friends.

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It takes a long time for the wall to crack and Sheldon to show his appreciation for those that enrich his life,but in time Sheldon realizes that without Leonard and the others, his life would be barren. His meeting with an eccentric mathematician who has chosen self-imposed exile shows Sheldon just how grateful he is for his friends, even if that won’t stop him from complaining.

2Sheldon Opens Up Emotionally

Emotionally stunted would be a generous description of Sheldon in the early episodes. From the first timethe opening themeplays until the finale, his friends regularly compare him to a robot for his almost total emotional disconnect,a disconnection that regularly leads to him hurting the feelings of those around him.

Leonard, Wil Wheaton, and the university HR rep are only a few of the targets of Sheldon’s careless sniping. By the end of the series, Sheldon has gained a significant appreciation for the way that his words and actions affect those around him. He is at last well enough in touch with his feelings to be able to express his needs and empathize with others.

Bernadette, Howard, Leonard, Penny, and the others hang out in The Big Bang Theory

1Sheldon Falls In Love

Howard and Raj might have brought Sheldon Cooper and Amy Farrah-Fowler together, but what kept them together was love, a feeling that no one thought Sheldon possessed. Their courtship might have made tortoises look like the Flash, but advance it did. From its robotic beginning to awkward flirtation, the first, tender touches, and their eventual union,nothing changed Sheldon more dramatically than falling in love with Amy.

Not only did their romance require him to open up emotionally, but it also required him to get over his fear of germs, physical contact, and intimate social situations. That Sheldon would overcome some of his worst fears in the name of loving Amy is a testament to how much he changed, and how worth it that change was.

Leonard, Penny, Sheldon, and Amy have an intense talk in The Big Bang Theory

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Sheldon cuddles with Amy on the couch in The Big Bang Theory