Another possibility is a jealous rival. Maybe there's someone who is jealous of Gohan's power or his relationship with certain characters. This rival could do things to annoy Gohan and push him to the edge of his temper.
A new player on an opposing team could be the cause. This new player might be overly cocky and disrespectful towards Kuroko during a game. They could constantly taunt him about his lack of presence, which finally gets on Kuroko's nerves and makes him mad.
It could be Vegeta. Maybe Vegeta does something really underhanded like stealing Goku's senzu beans or trying to take all the credit for a victory that Goku also contributed to. Goku, being a fair - minded person, would get angry at such behavior.
One of his friends could be the cause, accidentally. Maybe a friend makes a deal with a shady character without realizing the consequences. This deal ends up putting everyone in danger, and Yami gets mad at his friend's naivete and the mess they've created.
It might also be that Spongebob has made a series of small mistakes that have piled up over time. In the fan fiction, he could keep forgetting to do simple things like his job at the Krusty Krab properly, or he's always late for important meetings. This cumulative effect of his carelessness could lead to everyone getting frustrated and mad at him.
Mad God was a Chinese web novel that told the story of a young man named Kuang Kuang who was constantly struggling between the rise and fall. The following are the characters in the novel:
[Insolent: The male protagonist has a mysterious background and a special talent. He is one of the most powerful martial artists in the world of Mad God.] He had a strong sense of justice and responsibility.
Lin Yifeng: The famous martial dao master in the Mad God World is a legendary figure. He had taught Zhang Kuang many martial arts and hoped that he could become the strongest martial artist in the Mad God World.
Bai Jingjing: Lin Yifeng's wife is an outstanding martial arts expert and a well-known figure in the Mad God World. She and Lin Yifeng loved each other and faced all kinds of challenges and tests in the world of Mad God together.
[Blue Drip: Bai Jingjing's friend is a young martial arts expert and a well-known figure in the Mad God World.] He had a lively personality and was good at socializing. Like Bai Jingjing, he was also an outstanding martial arts expert.
[Xiao Yan: The male lead is a practitioner from another world who possesses a powerful fire affinity strength.] He came to the Mad God World to meet Zhang Kuang, Lin Yifeng, and the others. Together, they embarked on a thrilling adventure.
[Mo Fan: Xiao Yan's senior brother is a powerful fire attributed cultivator and also Xiao Yan's teacher.] He taught Xiao Yan how to practice fire affinity strength and helped him grow into a powerful martial artist.
[Su Mei: Mo Fan's wife is an outstanding female cultivator with a strong Ice Attribute.] She and Mo Fan were in love, facing the challenges and trials of the Mad God World together.
[Zhao Ming: Su Mei's good friend is a young martial arts expert and a well-known figure in the Mad God World.] He was gentle, kind, and righteous. He was an outstanding martial arts master like Su Mei.
It could be Perry the Platypus, in a really unexpected turn. Maybe Perry has to keep some secrets from Phineas for his spy work, and one day those secrets are revealed in a way that makes Phin feel betrayed. This would definitely make him mad.
It could be that Ron's actions were causing problems within the Order of the Phoenix. If Ron was being stubborn and not following the plans or orders set by the Order, which Sirius is a part of, Sirius might get angry. He would be frustrated with Ron for not being a team player and potentially endangering the mission and the lives of others.
One reason could be ChiChi's overbearing nature. She is often very strict about Goku's training and how he spends his time. In fanfiction, this could be exaggerated to the point where Goku finally gets fed up. For example, if she constantly nags him about not doing enough chores around the house instead of training, it might push Goku to his limit.
Let's say Annabeth put Percy's friends in danger without his knowledge. Percy is very loyal to his friends, and knowing that Annabeth's actions could have hurt them would surely make him angry at her.