Maybe Harry tries to reason with the troll. He could use his magic skills to calm the troll down and prevent it from causing more chaos.
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.
Well, he might try to tame the dragon. In some fanfictions, Harry could use his magic skills to communicate with the dragon on a deeper level, perhaps to gain its trust and make it an ally.
In some fanfictions, Harry Potter might learn some hidden secrets about the wizarding world's economy from the goblins. The goblins are known for their control over Gringotts and have a deep understanding of magical treasures. Harry could discover a new plot against Hogwarts related to a valuable artifact hidden in the vaults.
Perhaps Harry Potter talks to the dragon to enlist its help in finding a powerful magical object. Dragons are known to guard treasures. He could be on a quest for a Horcrux or some other important item. The dragon might initially be hostile but as they talk, it starts to trust Harry. Their conversation could involve exchanges about the power of magic, the dragon's own experiences in the magical world, and how they can both benefit from working together.
Well, in the fanfiction, Harry might seek Merlin's advice on dealing with dark magic threats. Merlin, being an ancient and powerful wizard, could offer unique insights that help Harry in his battles.
In some fanfictions, Harry might seek Snape's advice on how to deal with the remaining dark magic threats. Since Snape was so knowledgeable, his portrait could offer unique insights.
Well, he might be really confused at first. Fanfiction often takes the original story in different and sometimes wild directions. He could be shocked to see how some fans have imagined his relationships or new adventures that are quite different from his own experiences.
Well, he might be tempted by the dark magic within the Horcrux. It could try to manipulate him, maybe show him false visions of power or ways to defeat Voldemort that are actually leading him astray.
Well, he might be given a dangerous mission. Maybe he has to infiltrate a Death Eater stronghold or protect a crucial magical artifact.
In fanfiction, when Hermione talks to a Death Eater, she might try to persuade the Death Eater to abandon their dark ways. For example, she could use her intelligence and knowledge of the wizarding world to show the Death Eater the error of their beliefs. Maybe she would bring up the harm that Voldemort has caused and how following him is only leading to destruction.