In a fanfiction, the plot could revolve around Yuji and Nobara being sent to a different dimension. In this dimension, the rules of jujutsu are different. They have to adapt quickly and find a way back home. During their time there, they meet strange versions of their friends and enemies. They must use their wits and powers to survive and figure out how to return to their own world. This experience changes their relationship and makes them stronger as a team.
One idea could be a story where Yuji and Nobara go on a special mission together in an unknown location filled with new types of curses. They have to rely on each other's strengths more than ever.
There's 'Yuji and Nobara: Unseen Connections'. This fanfic delves deep into their friendship that could potentially turn into something more. It has some really interesting scenarios where they rely on each other's strengths and learn from their weaknesses.
Itadori did indeed die in the manga. His death had a significant impact on the story and the other characters. It was a turning point that led to many new developments in the plot.