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.
In this particular fanfic, Harry might have undergone some special training. Perhaps he has been taught by a very powerful and unorthodox wizard or witch. This training could have given him the knowledge and skills to understand the true nature of dementors better. He then uses this understanding to develop a method to kill them. For instance, he may have learned how to disrupt the very essence of what makes a dementor exist, like finding a way to break the connection between their form and the negative energy they feed on.
One consequence could be that the wizarding world is in shock. Dementors are usually just sent away or repelled, not killed. So, the Ministry of Magic might be very concerned about this new development and start to investigate Harry.
Well, in some fanfictions, Harry might use a super - powered Patronus. His Patronus could be stronger than usual, perhaps due to some newfound magic or a special connection he has developed. It could be so powerful that it simply overpowers the dementors and destroys them.
It could also be due to his own inner strength and growth as a wizard. Harry has faced so many challenges and traumas throughout his life. His experiences might have awakened a latent power within him that allows him to control dementors. His strong willpower and determination, which have been developed over years of fighting against the dark forces, could be the key factor in this newfound ability.
One way is through group support. If characters are together, they can draw strength from each other. For example, Hermione could use her knowledge to come up with a plan. Ron could offer his loyalty and courage. And they could all hold hands and face the Dementors together. Also, they might find some magical artifacts that can help, like a special amulet that gives them a sense of calm when Dementors are near.
In many fanfictions, Dementors are used as a tool to create a sense of despair. For example, when a character is facing a Dementor, their worst memories are brought to the surface, and this can be used to develop the character further. The fanfictions might also show how different characters react to the Dementors in different ways. Some might be paralyzed with fear, while others might try to fight back using magic like the Patronus charm.
Well, it could change the plot in many ways. For example, he might be able to negotiate with them. Maybe he can convince them not to attack people, which would make Hogwarts a much safer place. He could also learn more about their origin and motives directly from them, instead of just speculating as others do.
It's often described as an icy - cold and terrifying experience. The Dementors are usually depicted as hovering over the female Harry Potter character, their hooded forms menacing. The Kiss itself might be described as a sort of draining sensation, like all the warmth and hope being sucked out of her.
One consequence could be that the wizarding world starts to view him with even more suspicion and fear. People are already afraid of dementors, and if Harry can control them, they might think he's becoming too powerful or even turning to the dark side.
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 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.