Warning: Spoilers ahead for the latest episode of The Big Bang Theory. Be sure to come back once you've caught up!
When Young Sheldon began last year, many fans were surprised to find out that Sheldon Cooper actually had a best friend when he was a kid, because he never spoke about Tam to any of his adult friends on The Big Bang Theory. Well, we just found out why that is, and the reason is pure Sheldon. It turned out that Sheldon has been mad at Tam for 20 years, and the latest episode revealed what happened between the childhood buddies to cause such a rift.
Right when the show starts off, Sheldon is telling Amy how he's making their wedding photos better by adding people to them who didn't have the opportunity to come to the service. Since this is Sheldon we're talking about, this doesn't mean inserting shots of absent friends or family, but icons that Sheldon looks up to, like the Wright Brothers. A message then comes in from Tam, which Amy reads, telling Sheldon that he's coming to visit CalTech with his son and would like it if Sheldon could show them around.
When Amy asks who Tam is and Sheldon tells her that he was his "best friend in the whole world" when he was in high school, Amy wonders aloud why he's never mentioned him. It then becomes very clear that Tam angered Sheldon, because he yells his name five times really fast and stomps off to their bedroom.
Not to be deterred, Amy heads across the hall, and asks the gathered couples if they've ever heard of Tam, but they haven't either. Later, after Leonard notes to Howard and Raj that he figured there was nothing else to learn about Sheldon since he even knows all about his bowel movements, they place a video call to Sheldon's brother, George, to see if he knows why they had the falling out, but he's in the dark as well.
Fortunately, George reminds the guys about Sheldon's enemies list, and when they get off the call Howard manages to find Tam listed there (after going through a few digital hoops to access the online data), but all it says for a reason is "he knows what he did." But, all was not lost, as Raj had the bright idea of just asking Tam what happened all those years ago when they find him on campus the next day.
Well, if you think the answer was cut and dry, you must have already forgotten that this is Sheldon we're talking about. Tam had no idea Sheldon was even mad at him, and when Sheldon confronts him, asking what happened when he moved to California, all Tam can think to say is, "I stayed in Texas?" Of course, this makes Sheldon walk off in a huff, without it ever occurring to him that he never made his feelings clear to Tam all those years ago.
As it turned out, when Sheldon got accepted to CalTech, he was nervous about moving away from home, especially considering how hard it is for him to deal with people and make friends. So, he asked Tam to move with him and he had accepted. The problem, though, came that summer when Tam found himself with a new girlfriend. When it was time to move, obviously, Tam stayed in Texas to keep seeing her. And, this was despite all the pamphlets Sheldon had given him about STDs. The nerve of that guy, right? Seeing as how Sheldon considered their moving to California together to be a done deal, he was hurt, added Tam to his ever-growing list of enemies and vowed to never speak to him again. One-sided feud? Established.
When he relays this information to Amy, she points out that Sheldon's life might not have been as good as it is now if he had spent the past 20 years only relying on Tam and never making new friends. This led to Sheldon imagining what his life would have been like, which we see via a montage of well-known old scenes from the show (like when Sheldon finally fully accepted Penny and awkwardly hugged her), with Raj, Leonard and Howard removed but Tam added. Clearly, Sheldon wouldn't have changed as much as he has over these 11 seasons without the input of his circle of friends. But, Sheldon has always been stubborn, and he tells Amy his life would have been just as cool.
The last few minutes saw Sheldon forgiving Tam for not following through on the move to California, while Tam tells Sheldon he did nothing wrong in falling in love and wanting to stay with his girlfriend. Tam also told him that everything clearly turned out well for Sheldon and for himself, but Sheldon (showing that stubborn streak again) refuses to admit that Tam's life with his family in Texas is anywhere near as good as what he could have had if he'd moved with him.
So, with Tam and Sheldon finally made up, does this mean we might see more of the high school buddies communicating in Season 12? There's no way to tell right now, but the final season of The Big Bang Theory is sure to be full of surprises for fans. Who knows, since all fences have been mended and Tam has surely been removed from Sheldon's enemies list, maybe he'll think to give the guy a call if (or when) he and Amy find themselves on the path to procreation. At any rate, heaven knows that Leonard would love to have another person to spread best friend duties around with, even if the guy is several states away from Sheldon.