Perhaps the fanfic is about Buu waking up and being confused by the events of the Cell Saga. He might not understand the conflict between the androids and the Z - fighters. So, he could start interacting with different characters in his own strange way, like befriending some of the minor characters or causing unexpected mayhem just because he doesn't know any better.
In this 'buu wakes up in cell sags fanfic', Buu might wake up disoriented in the cell. He could start to explore his surroundings and find that the cell has some sort of magical or technological elements that are preventing him from leaving easily. As he tries to break free, he might encounter different challenges. There could be traps or puzzles that he needs to solve. And perhaps his waking up in the cell is part of a bigger plan by some powerful being, and Buu has to figure out what that plan is and how to stop it.
The main characters are clearly Fat Buu and Dr. Briefs. Fat Buu is a powerful and somewhat goofy character in the Dragon Ball series. Dr. Briefs is a brilliant scientist.
In this fanfiction, Fat Buu might befriend Dr. Briefs. They could have some comical exchanges. Maybe Fat Buu would be curious about Dr. Briefs' inventions and get into all sorts of wacky situations while exploring them.
One potential conflict could be Majin Buu's unpredictable behavior. He might accidentally break something important in Dr. Briefs' lab, which would anger Dr. Briefs.
In this fanfiction, Majin Buu might be curious about Dr. Briefs' inventions. Maybe he'll accidentally cause chaos in Dr. Briefs' laboratory while exploring all the cool gadgets.
Perhaps in this fanfiction, Cell somehow ends up in Bulma's laboratory. She initially panics but then realizes she can study Cell. Cell, on the other hand, is interested in Bulma's scientific knowledge and they start a strange alliance that eventually turns into an unexpected friendship.
There's a possibility that an evil scientist from another planet could be the main antagonist. This scientist wants to use Bulma's knowledge and Cell's power for his own evil experiments. So he tries to break up their partnership and capture them both for his own purposes. He sends his minions after them and creates various obstacles for Cell and Bulma to overcome.