Well, 'percy gets pissed' in a fanfiction could potentially explore Percy's character in a different light. Maybe he's been wronged in some way in the fan - created universe, like betrayed by a friend or faced with a difficult situation that makes him lose his temper. It could then lead to all sorts of plot developments, such as him seeking revenge or trying to overcome his anger in a journey of self - discovery.
Percy is surely a main character in this fanfiction. Depending on the universe it's set in, if it's related to a series like Percy Jackson, characters such as Annabeth, Grover, or his other demigod friends might also be important characters. They could either be the cause of Percy's anger or the ones who try to calm him down and help him through his angry state.
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.
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.
One reason could be betrayal. If someone he trusted, like a fellow ninja or an old acquaintance, turned out to be working for his enemies, that would surely make him pissed. It's a huge blow to his trust, which is a big part of his character.
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.
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.
Maybe he'll go on a rampage in the fanfiction world. He could start using his powerful jutsu to show his anger, like unleashing a Rasengan on the source of his annoyance.
Well, in a 'naruto gets pissed fanfic', Naruto might get angry over various things. It could be because of an enemy taunting him about his past, like how he was an outcast in the village as a child. He could also get pissed if his friends were in danger and he felt powerless to help them right away.
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.