Another reason could be that Harry sees the Order as being too cautious or old - fashioned in their approach to fighting Voldemort. He might believe that their traditional methods are not enough to defeat Voldemort quickly and effectively, and this lack of progress makes him angry at them.
Maybe he feels that the Order is keeping secrets from him. In many fanfictions, Harry can be a character who values honesty and when he discovers that the Order, which he may consider an ally, is hiding things from him, it can make him angry.
In some fanfictions, Harry Potter might be angry at the Order because he feels they are keeping secrets from him. He is used to being in the thick of things and when the Order withholds information, it can make him feel left out and untrusted.
One common theme is justice. When Harry is angry, it's often because he sees an injustice, like discrimination against certain groups in the wizarding world. Another theme could be protection. His anger might be triggered by a threat to his friends or Hogwarts, and he becomes determined to protect them. Also, self - discovery can be a theme. Through his anger, he might learn more about his own limits and capabilities.
In a dark corner of Hogwarts, Harry was fuming. Malfoy had once again taunted him about his parents. Harry's eyes blazed with anger. Without a second thought, he lunged at Malfoy, his wand at the ready. 'You won't get away with this anymore, Malfoy!' he shouted. Magic crackled in the air as they dueled, Harry's newfound determination pushing him forward.
One common theme is revenge. Since Harry is angry, he often seeks revenge against those who have wronged him or his loved ones. Another theme is self - discovery. His anger makes him question his own identity and values. For example, in many fics, he might wonder if he's becoming too much like the dark wizards he fought against because of his anger.
In some fanfictions, Harry might be angry with Ron and Hermione if he feels they are keeping secrets from him. For example, if they discover something important about Voldemort's plans but don't share it right away, Harry could get angry. He's used to relying on them and when that trust is broken, even if it's a misunderstanding, his anger can flare up.
His anger could also cause a rift within the group. His friends might be caught in the middle, not knowing whether to side with Harry or the Order. This could lead to some tension and arguments among them. Like Hermione might try to reason with Harry, but Ron could be more on Harry's side, causing a divide.
One common theme is betrayal. Harry often feels betrayed by those he trusts, like the Ministry of Magic or certain teachers, and his anger stems from that. For example, in some fanfics, he discovers that they have been using him for their own purposes.
One popular 'Harry is angry' fanfiction could be 'When Harry's Rage Unleashed'. It explores a situation where Harry gets extremely angry due to some misdeeds against his friends at Hogwarts. Another might be 'Harry's Angry Outburst' which details his reaction to unfair treatment within the wizarding community. There's also 'The Angry Harry Chronicles' that follows his angry moments and how he overcomes the negative emotions through his journey.