How Young Sheldon's Tam Returns On The Big Bang Theory

Sheldon Cooper (who's played by Iain Armitage and Jim Parsons at different stages in his life) didn't have many friends growing up, but the boy genius bonded with one person after being fast-tracked to high school. Tam Nguyen (Ryan Phuong) is introduced in "Young Sheldon" Season 1 and hits it off with Sheldon over comic books and their other nerdy interests. Outside of Tam being one of the few humans Sheldon tolerates, though, they aren't super close. However, they were close enough for Sheldon to hold a lifelong grudge against his old classmate, which we learn about in the 12th and final season of "The Big Bang Theory."

Adult Tam (Robert Wu) appears in Season 12, Episode 4, "The Tam Turbulence," to visit his old friend at CalTech, but he doesn't receive a warm welcome. Simply put, Sheldon is mad at Tam for going back on his promise to attend CalTech with him back in the day, as he met a girl and chose to stay in Texas. This angered Sheldon, as he didn't want to be separated from his buddy after moving to a new state, especially not over something as insignificant as romance.

Of course, Sheldon never expressed these feelings to Tam, who didn't find out about their feud until the aforementioned "Big Bang Theory" episode, which is set 20 years after the events of their last exchange. Despite having lost touch with his friend, however, Tam is given a pretty sweet story in the grand scheme of things.

The real reason Tam doesn't get mentioned on "The Big Bang Theory" until Season 12 is due to him being specifically created for the prequel series. After all, "Young Sheldon" only came to fruition thanks to a random Jim Parsons incident that inspired Chuck Lorre and co. to make a new sitcom, so the Tam character wasn't even in their mind when they came up with the idea for "Big Bang Theory." However, the spin-off forced the creators to create more synergy between both shows, and Tam returning is a prime example of that.

"The Tam Turbulence" confirms that the titular character got married and had kids, giving him a life that he loves. What's more, he even makes amends with Sheldon before he returns to Texas and the story ends on a happy note, with Tam no longer included on his old pal's enemy list, and Leonard Hofstadter (Johnny Galecki) driving him to the airport.

"Young Sheldon" also changed a controversial "Big Bang Theory" storyline that led to Sheldon holding a grudge against his dad for years. Unfortunately, he didn't get a chance to resolve these issues prior to George Sr.'s heartbreaking death in "Young Sheldon" Season 7, and it turned out to be a big misunderstanding.

Both "The Big Bang Theory" and "Young Sheldon" are currently streaming on Max.