Well, in certain fanfiction plots, it could be due to interference in his personal life. For instance, if the Ministry of Magic starts to impose strict rules on his after - school activities, which he views as an infringement on his freedom. Or perhaps if a new teacher at Hogwarts has a vendetta against him and is constantly giving him a hard time, that would surely make Harry pissed off.
You could have Zuko be constantly outsmarted by his enemies in really dumb ways. Also, you could make his backstory completely different in a bad way, like making his mother leave him because she didn't love him. And then, you could make him lose his temper at every little thing, which is not in line with his growth as a character in the original story. This would really get on the nerves of Zuko fans who love his character development.
One way could be to make Zuko constantly lose his battles in a really uncharacteristic and stupid way. Another way might be to give him a really cheesy and out - of - character love interest. And a third way could be to have his father be nice to him all of a sudden for no good reason.
One way could be constantly misinterpreting Iroh's character. For example, making him overly cruel when he is known for his kindness. Another way might be writing out - of - character relationships for him, like having him suddenly be at odds with characters he was always friendly with in the original. And also, completely ignoring his backstory and the development he went through in the series can piss off fans of Iroh fanfiction.
Well, one key element could be the strong and unique nature of the Uzumaki clan. They are known for their vitality and powerful chakra. In this fanfiction, it might focus on how Naruto, being an Uzumaki himself, has certain traits that make him formidable. Another element could be the situations or characters that might potentially 'piss off' an Uzumaki, like enemies underestimating their power or messing with their loved ones.
It could also be due to the fanfic's poor writing quality. If the grammar and spelling are atrocious and it's hard to follow the story. When it comes to Naruto, fans have high expectations. So, if they can't even understand what's going on with Naruto in the fanfic because of bad writing, it can lead to a 'pissed off' reaction.
One reason could be Hermione's excessive worrying. She often frets over small details and Harry might get tired of it and tell her off. For example, if she keeps nagging about the proper way to perform a spell when they are in a hurry during a dangerous situation.
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.
One reason could be that she was too engaged in an activity and didn't want to take a break to use the bathroom, like the girl at the fair who was having too much fun. Another reason might be nervousness, similar to the girl in the school play who was so nervous she forgot about using the bathroom.
She could also lie to gain an advantage in a situation. Maybe there's a competition or a mystery they're trying to solve, and she thinks lying to Harry will give her the upper hand. For example, if they're competing to find a hidden magical object, she might lie about where she's looking to throw him off.
One possible reason could be to save someone else. Maybe a friend or a loved one is in danger at the base of the tower and Harry believes jumping is the quickest way to reach them. For example, if there's a dark spell about to be cast on Hermione and the only way to stop it in time is for Harry to reach her instantly.