Sheldon changes a lot during the course of The Big Bang Theory. His social skills improve, his patience increases, and so does his appreciation for all the things his friends do for him. In other words, he becomes more caring, sensitive, empathetic, and grateful, especially towards his former roommate and best friend, Leonard.
If the Sheldon from season one saw how much he would change, chances are he’d try to stop it. Similarly, if season one Sheldon knew about Leonard’s future, he’d be in shock and even slight disgust at his bespectacled friend’s choices. But deep down, he’d also smile at the knowledge that Leonard eventually finds his happy ending.
Would Hate: Leonard Is No Longer There For Him 24/7
At the beginning of the show, Leonard is always there for Sheldon. Partly because of their living arrangements and partly because of the Roommate Agreement. But Sheldon knows that Leonard will always drive him where he needs to go, talk to him about comic books, and generally spend his free time with him.
By season twelve, both friends have gained a great deal of independence from each other. And while final-season Sheldon went through a twelve-year process to get there, season-one Sheldon wouldn’t know it and would simply see a separation between two friends who used to do everything together.
Would Love: Leonard And Beverly Fixing Their Relationship
From day one, Sheldon genuinely cares for Leonard and has his best interest at heart. Being his best friend, he knows how difficult Leonard’s childhood was, and while he feels a great deal of respect towards Beverly, he also knows she wasn’t exactly the best mother to Leonard.
In season twelve, Leonard and Beverly finally find common ground and begin healing their relationship. Season-one Sheldon wouldn’t understand why Leonard needs his mother’s approval, but would certainly be happy that he finally got it.
Would Hate: Penny’s Prominent Role In Their Lives
Penny and Sheldon become incredibly close during the course of the series, to the point where he actually considers her one of his two best friends. Indeed, she seems to understand him better than most people, even Leonard, and eventually assumes the role of an older sister to him.
In season one, Sheldon and Penny had yet to develop their bond, and so he would be puzzled and perhaps angered by how much his future self relies on Penny. He’d probably blame Leonard for her presence in their lives, giving him another reason to resent his friend.
Would Love: Leonard Still Loves The Same Things
For all the things that change in their lives, Leonard and Sheldon remain passionate about the same things for most of the show. Even in season twelve, their love for comic books, superheroes, Star Wars, and Star Trek is still there, confirming that some things indeed never change.
Sheldon would breathe a sigh of relief knowing that, despite the years, Leonard still knows what’s good. He’d also love the fact that a new Star Wars trilogy came out, and would probably collapse when he found out how divisive and controversial those films were.
Would Hate: They No Longer Live Together
If there’s one thing Sheldon would absolutely loathe, it is seeing Leonard living with Penny and not him, and in their old apartment no less. He’d consider it a violation of the Roommate Agreement and simply wouldn’t understand how on Earth that happened.
Despite being a lot more robotic and stoic, season-one Sheldon would probably feel very hurt by Leonard’s living situation. He wouldn’t show it, and instead would go to the pet store and buy dozens of kittens, or perhaps he would buy another loom and knit everyone matching serapes.
Would Love: Leonard Stands Up For Himself
Season-one Leonard is gentle, shy, and has trouble standing up for himself. During the course of the show, he faces several of his own fears and insecurities, although he also becomes more compliant, especially towards Penny. In season twelve, he finally puts his foot down at the university and even manages to secure a co-lead position in an upcoming experimental physics project.
Sheldon would applaud his friend’s newfound confidence and would actually mean it. He’d also be happy to learn that Leonard still works at the university alongside him.
Would Hate: Leonard Will Be A Father
Sheldon dislikes babies in the earlier seasons. He has neither the patience nor the desire to deal with them and considers them a nuisance rather than a privilege. In the Pilot episode, Sheldon even mocks Leonard’s statement about his hypothetical future children with Penny, believing it would never happen.
Fast forward twelve years and Penny is expecting her first child with Leonard. Season-one Sheldon would be appalled at the news, reacting with cruel disbelief. He’d probably mock the couple’s parenting skills before making it clear he would not be present for the child’s upbringing.
Would Love: Learning They Are Still Friends
Through highs and lows, Leonard and Sheldon’s friendship remains constant. In fact, their bond strengthens with the years, as they both become mature and responsible adults. The ending of the show makes it clear that, no matter what the future holds for them, they’ll always be friends.
Season-one Sheldon would be happy at this. He is a creature of habits who does not react well to change. Knowing that, despite all the chaos in their future lives, Leonard is still his closest friend would give past Sheldon a sense of certainty and security to deal with his unpredictable future.
Would Hate: Seeing Leonard Married
Season-one Sheldon thinks marriage is a mistake. Because of his own experience watching his parents’ marriage disintegrate, he considers the whole thing ridiculous, a senseless and ultimately futile attempt at committing to another person.
Seeing Leonard married to Penny would be a huge blow to Sheldon. He wouldn’t understand how the relationship came to happen, much less how they made it all the way to the altar. He would also believe the union wouldn’t last and would make sure everyone heard it.
Would Love: Seeing Leonard Happy
Eventually, past Sheldon would have to swallow his pride and admit that future Leonard is indeed happy with his new life. The genius wouldn’t understand it, of course, and would constantly complain about how no one thinks of him when pursuing their own happiness.
Deep down, however, Sheldon would feel genuinely happy for his friend. Seeing Leonard so changed and fulfilled would be scary for season-one Sheldon, though, and his conflicting emotions would make things very difficult for him.