Sheldon Cooper

In 1989, at 9, Sheldon starts high school in Medford, in the same grade as his older brother, Georgie. His mom, Mary, is a devout Baptist who shields him from everything; his dad, George, a football coach, has no idea what to do with a son who corrects his teachers. His twin sister, Missy, has the people smarts he lacks, and his grandmother, Meemaw, calls him Moon Pie.

Friendless, he tries to follow a self-help book and ends up bonding with Tam. He discovers comic books, spends a stretch at a school for gifted kids in Dallas and comes home. When high school gets too easy, he starts sitting in on Dr. Sturgis's physics classes at the local university, and finds his first mentor there.

After graduating high school as valedictorian, Sheldon enrolls at East Texas Tech while still a kid. A philosophy class sends him into an existential crisis, but he badgers his way into being Dr. Linkletter's lab assistant and gets a dorm room. He competes with Paige, builds a database that flops and spends a summer studying in Germany, where he learns for the first time what it's like to be the weakest student in the room.

A published paper brings grad school offers, and he picks Caltech. Shortly before the move, his father dies of a heart attack. At the funeral, Sheldon can only imagine what he could have said to him. To please his mother, he agrees to be baptized, then leaves for California on his own at 14.

In Pasadena, Sheldon shares apartment 4A with experimental physicist Leonard Hofstadter under a roommate agreement that covers everything from guests to bathroom use. His regular crew is Howard Wolowitz and Raj Koothrappali. Life changes when Penny moves into 4B. Sheldon complains, but builds an odd friendship with her: she sings Soft Kitty when he's sick, and he knocks three times calling her name.

In the first season, he gets fired for insulting his new boss, and his mother flies in from Texas to fix it. Later he lands funding for a three-month North Pole expedition to hunt magnetic monopoles and drags Leonard, Howard and Raj along.

The expedition comes back with data his friends faked, and Sheldon flees to Texas in humiliation. Soon after, Howard and Raj sign him up for a dating site and he meets neurobiologist Amy Farrah Fowler, who thinks almost the way he does. At first they're just friends. When Amy goes out with Stuart, Sheldon feels jealousy for the first time and asks her to be his girlfriend with a relationship agreement.

Their first real kiss comes on Valentine's Day. Not long after, fed up with string theory and too much change, he boards a train and disappears for weeks. Back home, he secretly buys a ring, but Amy asks for a break before he can say anything. They spend months apart, reunite and spend their first night together on her birthday.

Sheldon and Amy try living together in Penny's old apartment and decide to stay. When she spends the summer at Princeton and Ramona Nowitzki kisses him, he realizes what he wants: he flies to New Jersey and proposes to Amy at her front door.

Wedding planning exposes his jealousy of Amy's career and an old wound: Sheldon hasn't spoken to his brother Georgie in years. At Mary's insistence, he goes to Texas with Leonard to make peace. At the wedding, officiated by Mark Hamill, he frets over his crooked bow tie and, with Amy, spots an idea about super-asymmetry. They put the physics aside and get married.

The super-asymmetry theory is confirmed by two physicists who try to take the credit. Sheldon and Amy fight through disputes, plagiarism accusations and their own nerves until they win the Nobel Prize in Physics. In Stockholm, Penny reveals she's pregnant, and Sheldon reacts by thinking only of himself. Amy calls him out: his friends have always put up with him.

In his speech, Sheldon drops the remarks he'd written about himself and thanks his friends, calling them his family. The story ends with the whole gang gathered in apartment 4A, eating together like always.

Sheldon and Leonard are named after actor-producer Sheldon Leonard. Jim Parsons won four Emmys for lead actor in a comedy and a Golden Globe for the role, and he narrates Young Sheldon, where Iain Armitage plays young Sheldon. 'Bazinga' is a registered Warner Bros. trademark.