The author can use vivid descriptions of his facial expressions. For example, 'Harry's face turned red, his eyes blazing with fury as he clenched his fists.' This gives the readers a clear visual of his anger.
By showing how his anger affects his relationships. When Harry is angry, he might snap at his friends like Hermione or Ron. This can create tension in the story. The author can also show how his anger is a driving force for change. Maybe his anger at the injustice in the wizarding world makes him more determined to fight against the dark side, and this change in his attitude can be shown through his interactions with other characters and his decision - making process.
The author can use strong dialogue. For instance, having Tony shout out angry words with a lot of force and passion. Words like 'I've had enough!' or 'You'll pay for this!' can quickly convey his anger. Also, the use of expletives (if appropriate for the rating of the fanfiction) can enhance the sense of his fury.
Another way is to contrast his normal, bespectacled self with this new, glaring - without - glasses version. Maybe in the story, his friends are so used to seeing him with glasses that when he glares without them, it has a different impact on them. The writer can use this to create interesting character interactions and development within the fanfiction. For instance, Hermione might be initially shocked but then realize the new level of intensity Harry has reached.
They can describe his physical symptoms well. For example, 'Harry's hands trembled uncontrollably as his chest tightened, making it hard to draw a full breath.'
The writer can use body language. For instance, they can describe how Harry's eyes look downcast, his shoulders slump, and he just shakes his head slightly instead of speaking. This non - verbal communication can show that he has chosen not to talk.
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.
Well, the author can use flashbacks effectively. Maybe show happy memories of James and then contrast them with his current state of depression. This will highlight how much he has changed. His speech can also be a tool. Slow, monotone speech, or long pauses before answering can show his mental state. Additionally, his attitude towards magic could change. He might lose his enthusiasm for it, which was once a big part of his life. For example, not being excited about new spells or magical creatures anymore.
Some authors might show it as a moment of vulnerability. Harry, who is often seen as brave, when he cries, it can be a sign that he's just a boy dealing with a lot. So the author may describe his tears as a silent stream running down his face, his eyes red and puffy, while he tries to keep his composure in front of others.
The author can use physical cues. For example, Kuroko might clench his fists tightly, a rare display of emotion from him. His normally calm blue eyes could narrow and become more intense. Another way is through his dialogue. He could speak in a sharper tone than usual, with shorter, more forceful sentences.
Using dialogue with other characters. For instance, if he has a conversation with Nico and he just breaks down while talking, saying things like 'I can't do this anymore' or 'I'm so tired of trying to be strong'. The interaction with another character can highlight the emotional intensity of his breakdown and how it affects those around him.
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.