A sense of powerlessness can also be a theme. When he's faced with situations where he can't immediately solve a problem or protect those he cares about, Harry might get pissed off. This often leads to him finding new ways to gain power or take control in the fanfiction.
One common theme is revenge. When Naruto is pissed off, often he's seeking revenge against someone who has wronged him or his friends. For example, if Orochimaru did something to harm Sakura, Naruto would be pissed off and his revenge - driven actions would be the focus. Another theme could be self - discovery. His anger might lead him to discover new powers or a new side of himself. Like his anger might unlock a hidden bloodline limit that he didn't know about before.
Another good one is 'When Harry's Temper Flared'. Here, it starts with a small incident in the Gryffindor common room that snowballs into a major event where Harry gets extremely pissed off. The writer focuses on Harry's relationships with his friends during this time of anger and how they react to his outbursts.
Sasuke could be the cause. If Sasuke were to betray Naruto again in the fanfiction, it would surely make Naruto pissed off. Their relationship is complex and Sasuke's actions have a big impact on Naruto.
The 'harry gets pissed fanfiction' might center around Harry experiencing a range of emotions that lead to him being pissed. It could be due to a betrayal, like if someone he trusted in the fan - created story did something against him. It might also be related to his goals being thwarted, for example, if he was trying to achieve something important and someone or something got in his way.
To find out the author of the 'harry gets pissed fanfiction', you could try searching on fanfiction platforms. Look for the story and check the details page. Usually, the author's name or username will be clearly stated there.
A new, powerful and arrogant villain introduced in the fanfic could be the cause. This villain could constantly mock Naruto and his ideals, and try to undermine his efforts to protect the village. Such blatant disrespect would make Naruto really pissed off as he is very protective of his home and the values he stands for.
One possible scenario could be that Naruto gets pissed off when he discovers someone has been spreading false rumors about his friends in the fanfiction. This would really push his buttons as he values his friends highly.
Maybe in the fanfiction, Nero has made some decisions that go against Trish's beliefs or values. For example, if Nero decides to trust a character that Trish knows is untrustworthy, it could make her angry.
Another reason might be related to his family. In some fanfictions, his parents' story or his relationship with his family members could be distorted. Harry has a strong connection to his family, especially his parents, and any wrong portrayal of that could make him pissed off.
In a 'naruto gets pissed off fanfic', one possible scenario could be that Naruto discovers someone has been slandering his friends behind their backs. He would get pissed off and confront the person directly, his eyes blazing with anger.