Well, in some fanfictions, Harry might use his quick thinking and knowledge of the troll's weaknesses. He could first distract the troll by making noise or using magic to create illusions, then when the troll is off - guard, he strikes with a well - aimed spell, perhaps a blasting charm. Also, he could have some help from his friends. For example, Hermione might provide some crucial information about trolls that helps Harry come up with a plan. Ron could be there to support Harry, maybe by providing a diversion while Harry gets in the perfect position to deliver the fatal blow.
In the fanfiction, there could be a range of consequences. On one hand, he could be seen as a hero by his fellow students. They might admire his bravery and his ability to take on a dangerous troll. However, the teachers may be more cautious. If Harry used excessive force or magic that was not in line with the school's code of conduct, he could be given detention or even face a disciplinary hearing. Also, depending on how the troll was killed, there could be some magical fallout. For example, if he used a very dark spell, it could have an effect on his own magical core or his relationship with magic in general. Moreover, the death of the troll might also attract the attention of other dark creatures or forces that were somehow related to the troll, putting Harry in further danger.
Well, in many such fanfictions, Harry might use his magic skills. He could cast a powerful stupefy spell on the troll to stop it in its tracks and then quickly lead Hermione to safety. Maybe he also uses his quick thinking and knowledge of the Hogwarts corridors to find a hiding place where the troll can't reach them.
In certain 'Harry kills the dragon' fanfictions, Harry could be given a special magical weapon specifically designed to slay dragons. He might have to go through a series of trials to figure out how to use this weapon effectively. It could be that the weapon has to be powered by his own magic and emotions. Once he masters this, he is able to take on the dragon and kill it. For example, the weapon might need to be charged with his feelings of courage and determination, which are strong in Harry, and then he uses it to strike a fatal blow to the dragon.
Often, in these fanfictions, Harry's knowledge of the Horntail's weaknesses plays a crucial role. He might have spent time researching about the Horntail in the library at Hogwarts. When it comes to the actual fight, he uses this knowledge. He aims for the Horntail's soft underbelly or its eyes, areas that are more vulnerable, and with a well - aimed spell or a thrust of a weapon, he kills the Horntail.
In many fanfictions, Harry might use his powerful spells like the Stunning Spell or the Killing Curse if the story allows for such dark magic use. He could also use his intelligence to outwit the dragon, perhaps finding a weakness in its armor or behavior pattern and then using a well - timed spell to defeat it.
Maybe he uses his charm and influence. If Harry is a popular or respected character in the fanfic, he could simply talk to the ones creating the troll humor and convince them to stop.
Well, it could be that in this fanfic, Harry has some sort of special artifact or weapon. For example, he might find an ancient magical object that has the power to vanquish dementors. He figures out how to use it and thus is able to kill the dementors. It could also be that he has made a special connection with some magical being or force that gives him the strength to take on the dementors in a more lethal way.
The other students would likely spread rumors. Some might idolize Hermione for her bravery in taking on a troll, while others might be afraid of her. This could lead to a change in her social standing at Hogwarts. She may become more isolated as some students avoid her, or she could gain a group of followers who admire her boldness.
He might approach it cautiously. After all, trolls are dangerous creatures. He could start by speaking in a calm voice, trying not to startle it.
He may use a powerful spell combination. For example, he could start with a Confundus Charm to confuse the Horntail and then follow up with a blasting spell to deal a significant amount of damage.