In some fanfictions, Harry Potter may draw on his experiences from the Triwizard Tournament. He could recall how he faced the Hungarian Horntail and use that knowledge to his advantage against this new dragon. For example, he might use his Patronus charm not just as a defense against Dementors but to disorient the dragon. Or he could use his ability to communicate with snakes (if he still has that ability in the fanfiction) to somehow trick the dragon into a vulnerable position and then finish it off with a well - aimed spell.
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.
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.
Well, in many fanfictions, Harry might use a combination of his existing skills and newfound powers. He could use his Parseltongue ability to communicate and perhaps distract the Basilisk, and then strike it with the Sword of Gryffindor. Another way could be that he uses some sort of spell he's been secretly practicing that gives him an edge in the fight.
It could be an entirely new type of dragon created specifically for this fanfiction. The author might have wanted to introduce a unique dragon with special abilities, like a dragon that can change its color to blend in with its surroundings or one that can breathe not just fire but also some kind of magical ice. Harry would then have an even greater challenge when trying to kill it with the sword.
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.
There's also a possibility that it's a Chinese Fireball. These dragons are very beautiful and powerful. In a fanfiction, the author might choose this type of dragon for Harry Potter to own because it would add an element of exoticism and grandeur to the story.
In some fanfictions, Harry Potter might die by dragon in a battle. Maybe he's outnumbered by a group of aggressive dragons and they overpower him. His spells might not be enough to fend them off, and in the end, a dragon's fire or a powerful attack could be his end.
It could be that the dragon was an egg he found by accident. He, being curious and having a soft spot for magical creatures, took the egg and hatched it, thus becoming the owner of the dragon. In the wizarding world, there are often unclaimed or lost magical items and creatures, and Harry might have just stumbled upon this dragon egg.
Well, in some fanfictions, Harry might use some hidden magic he discovers in Azkaban. Maybe he finds a way to turn the Dementors' power against Voldemort. Since Dementors can suck out a person's soul, Harry could somehow direct them towards Voldemort, weakening him enough to deliver the final blow.
It re - imagines him as having a more primal and powerful side. With his dragon half, Harry is no longer just a regular wizard. He has an innate fierceness that comes from the dragon part of him. This could make him more confident and less hesitant in dangerous situations.