The Big Bang Theory's spinoff, Young Sheldon, recently celebrated its 100th episode, which had some reveals that were associated with its predecessor. Seeing the changes in the Cooper family reminded fans of the future that Sheldon eventually has for himself; a future filled with academic achievements and friendship.
The power of friendship is a strong theme throughout TBBT, with a different pair gaining strength and popularity in each season. While Leonard and Sheldon had a strong friendship over the years, other duos outshined them at times.
Season 1: Howard & Raj
In season 1, fans were introduced to the friend group. Sheldon and Leonard were roommates who lived across the hall from their beautiful neighbor, Penny. And Howard and Raj were best friends who were also close with Leonard and Sheldon. The four guys all worked closely together in different departments at Caltech.
Although viewers were intrigued by Sheldon and Leonard's dynamic — due to how socially awkward Sheldon could be — all eyes were on Howard and Raj. Since Raj couldn't speak in front of women because of his selective mutism, he spoke through Howard. Howard and Raj were also single and on the hunt for companionship. Their interactions were hilarious, and their quotes proved Howard and Raj had the best friendship on TBBT.
Season 2: Penny & Sheldon
Longtime fans can agree that Sheldon and Penny had the sweetest quotes on TBBT because of their special friendship. In season 1, the two were learning more about each other but by season 2, they became far more comfortable than they could have expected.
Sheldon taught Penny how to game in 'The Barbarian Sublimation,' they created Penny Blossoms in 'The Work Song Nanocluster,' and they even gave each other memorable Christmas gifts, with Penny gifting Sheldon a napkin signed by Leonard Nimoy. Season 2 focused on the growing sister-brother bond between them.
Season 3: Sheldon & Raj
There were many sad things about Raj on TBBT because he never found the kind of love he had always hoped for. Luckily for him, he had the support of his friends — including Sheldon. Although Raj's best friend was Howard, Sheldon and Raj were close in season 3.
In this season, Sheldon saved Raj from being deported by giving him a job working under him at Caltech. On top of that, Sheldon joined Raj as his wingman when he wanted to meet a woman. Sheldon had his cold, selfish moments but he showed real respect for Raj in this season. In the end, Raj wanted Sheldon to find happiness so he signed him up on a dating website and introduced Sheldon to his future wife, Amy Farrah Fowler.
Season 4: Penny & Amy
Season 4 was when Sheldon and Amy's relationship timeline began on TBBT. After being set up on a date, they slowly got to know each other. The more comfortable Amy became with the group, the closer she got to Penny.
Penny was unsure of Amy at first because of how different they were, but their quirky bond was one of the best in season 4. They shared their first girls' night, Penny joined Amy on her first date with Sheldon, Amy asked Penny to join her in Big Sur for a mini-getaway, and more importantly, Amy realized that Penny still loved Leonard and did what she could to get the two together, despite Leonard being with Priya.
Season 5: Leonard & Sheldon
Leonard and Sheldon's friendship was strong because of Leonard's ability to handle Sheldon's, at times, annoying personality. In season 5, their bond took center stage.
In this season, Sheldon helped Leonard fight his childhood bully in 'The Speckerman Recurrence' and they came to a mutual understanding about their friendship (and roommate agreement) in 'The Friendship Contraction.' The two battled some snags in their friendship but conquered them and came out stronger.
Season 6: Penny & Bernadette
As a microbiologist, there were times Bernadette was the smartest in the room on TBBT. She was typically calm, cool, collected, and knew what she wanted. As Penny's best friend, Bernadette was the voice of reason in most situations, and this was shown in depth in season 6.
In this season, Bernadette was newly married and Howard was in space. Penny helped Bernadette sort wedding gifts, Bernadette helped Penny with community college, the two studied comics with Amy to understand them better, and the duo spent Valentine's Day together on a double date. Although Penny and Bernadette were close with Amy, it was their friendship that outshone others.
Season 7: Raj & The Women
Raj's best friend was Howard, but when Howard got married to Bernadette, their friendship took a backseat. In season 7, Raj realized that he enjoyed spending time with Penny, Bernadette, and Amy during their girls' nights because he was able to vent, gossip, and do the feminine things that Howard didn't want to do.
In season 7, Raj was protected by Penny after his breakup with Lucy and he cooked Thanksgiving dinner with Bernadette and Amy. Raj matured throughout TBBT due to his moments spent with his gals.
Season 8: Leonard & Sheldon
Leonard and Sheldon had one of the best friendships on TBBT. Although Sheldon annoyed Leonard, they needed each other in ways they didn't want to admit. In season 8, their admiration for one another was at its strongest.
In the season premiere, Leonard drove to Arizona to pick up Sheldon after he was robbed on a train. They also made a road trip to see Skywalker Ranch. But one of the best moments of friendship was when Leonard needed surgery on his nose and Sheldon was adorably concerned with the health and safety of his best friend. The surgery showed how close the two friends were.
Season 9: Bernadette & Amy
Fans loved the dynamic between Penny and Amy, but the friendship between Amy and Bernadette was underrated. In season 9, their bond really flourished.
Not only were Bernadette and Amy women in science who conversed about their jobs, but they also helped each other in their respective relationships. Bernadette helped Amy date again after her brief breakup with Sheldon, and she later prepared Amy after hearing that Sheldon was ready to take his relationship to the next level. At the end of season 9, Amy and Bernadette enjoyed time with Leonard's mom who applauded them for being high achieving couples.
Season 10: Leonard, Sheldon, Howard, & Raj
In season 10, everyone rallied around Howard when he had an idea for a guidance system that wasn't created yet. Howard and Sheldon finally found common ground when the latter agreed to help with the math.
For the majority of the season, Sheldon, Leonard, Raj, and Howard worked together on this guidance system that was later bought by the US Air Force. On top of working together, the group was there for Howard and Bernadette when they had their first child.
Season 11: Amy & Penny
In season 11, Amy and Penny's lighthearted friendship stole the show. With Amy being newly engaged, Penny helped her with her nuptials and epic bachelorette party since Bernadette was pregnant again with her second child.
Penny was instrumental in Amy's wedding and it was sweet seeing how far their friendship came after first being introduced in season 4.
Season 12: Sheldon & Leonard
In the final season, the focus was on Sheldon and Amy's Nobel Prize and the potential futures for everyone else. With such a big moment for Sheldon, it was clear that he was the show's main character despite being a part of an ensemble cast.
With conversations hovering around work, children, and relationships, Leonard and Sheldon supported each other when they needed it. Leonard helped Sheldon verify his research with Amy, and Sheldon cleared Leonard's mind when the possibility of being a sperm donor came up. In the series finale, Sheldon and Amy won their Nobel and Sheldon gave an endearing speech where he thanked his best friend, Leonard.