The uniqueness of their relationship. Tam and Sheldon are both very different characters. Sheldon is extremely intelligent but socially awkward, while Tam has his own set of qualities. Fanfictions that explore how they interact and complement each other are special. For example, Tam could help Sheldon in social situations that he struggles with, like understanding group dynamics at school.
Yes, it is based on the real - life experiences of the show's creator, Chuck Lorre, and Bill Prady, who drew inspiration from their own childhoods and the people they knew growing up. The show is set in a fictionalized version of the real world, but many of the characters and situations are inspired by real events.
Young Sheldon isn't based on real events. It's a fictionalized account that takes creative liberties to entertain the audience and doesn't draw from actual people or incidents.
In the novels so far, young Griff is alive. George R. R. Martin has left many plotlines open, including young Griff's. There are various speculations among fans. Some think he might play a significant role in the future battles and power struggles in the Seven Kingdoms. However, until Martin releases more of the story, we can't be sure if or how he will meet his end.
One great Young Sheldon Tam and Sheldon fanfiction could be one where Tam helps Sheldon with a difficult science project at school. Tam might bring in some unique ideas from his own background that Sheldon hadn't considered. Another could be a story about their friendship growing over shared interests in comic books, despite their different personalities.