Maybe Fudge was starting to turn against the wizarding community in more extreme ways. For example, if he was planning to persecute Muggle - borns more harshly or side with the Death Eaters secretly. Harry, being a defender of justice and equality in the wizarding world, would not tolerate such actions and might have been pushed to kill Fudge to stop his evil plans.
One common theme is power and corruption. Fudge is often depicted as being power - hungry and making corrupt decisions in fanfiction, just like in the original books. For example, some stories show him using his position to suppress information or manipulate other characters for his own gain.
The Weasley twins could be part of it too. Suppose Harry yells in excitement or anger about a new prank idea that the twins have come up with that might be a bit too dangerous. They could either encourage his yelling or try to tone it down, depending on their mood. And Malfoy might overhear Harry's yell and use it as an opportunity to taunt him, adding more conflict to the fanfiction.
In some fanfictions, Harry might use his first - hand experiences of Voldemort's return. For example, he could present the details of the graveyard encounter where Voldemort was resurrected. His eyewitness account, including the presence of Death Eaters, directly contradicts Fudge's denial of Voldemort's return.
It could also be related to the treatment of Harry's friends or allies. Suppose Fudge is persecuting Dumbledore or other Order of the Phoenix members. Harry, who is loyal to his friends and those fighting against the Dark Arts, would be enraged and yell at Fudge. He wouldn't stand for any harm coming to those he cares about, and Fudge's actions in this regard would surely provoke Harry's anger.
One possible reason could be copyright infringement. If the fanfiction uses too much of the original 'Harry Potter' material without permission, it might lead to a lawsuit. For example, if it uses the exact same characters in a way that goes against the original concept or if it borrows major plot elements directly.
Well, in many fanfictions, Harry might use his quick thinking and knowledge of magic. For example, he could use spells in unexpected ways to get around Fudge's plans. Maybe he uses a charm to make Fudge misinterpret a situation or forget an important detail. Harry is known for his resourcefulness, and against Fudge, he could use his skills to expose Fudge's wrongdoings or prevent Fudge from interfering in things that Harry believes are right.
Maybe she's yelling at Ron. Their relationship in fanfictions can be quite complex. If Ron says something insensitive or does something stupid, like forgetting an important task that could put their mission in jeopardy, Hermione would surely yell at him.
Perhaps in a 'harry potter yells fanfiction', Harry yells when he discovers that someone has been spreading false rumors about his friends. He could be in the Great Hall, stand up, and yell at the perpetrator, creating a big scene full of drama and conflict within Hogwarts.
Maybe Albus has done something dangerous or disobeyed Harry's instructions. For example, if Albus got involved with some dark magic related stuff without Harry's knowledge, that would surely make Harry yell at him.