Well, in some versions of this fanfiction, Harry might discover it by accident. For example, he could be in a situation where he's near a dragon and instead of the usual fear or aggression from the dragon, it seems to be communicating with him in a strange way. Maybe the dragon's eyes seem to be trying to convey a message, and Harry just somehow understands it, like he has an innate sense that he can pick up on the dragon's thoughts.
Perhaps he discovers it during a Care of Magical Creatures class when they are studying dragons. There could be a moment when the dragon they are observing focuses directly on Harry and starts making noises that he realizes are not just random growls but actual attempts at communication. He might start to notice patterns in the dragon's behavior and sounds that lead him to understand he can communicate with it.
In a lot of fanfiction, it's often through a near - death experience. For example, Harry might be in a situation where he is facing a dragon that is about to attack him. In that moment of extreme danger, he somehow makes a mental connection with the dragon and realizes he can talk to it. This kind of life - or - death situation often unlocks hidden powers in the Harry Potter universe, and this could be one way he discovers his ability to talk to dragons.
Yes, there are likely many 'Harry can speak to dragons' fanfictions out there. Fanfiction websites are full of creative takes on existing fictional universes. You can try searching on popular fanfiction platforms like Archive of Our Own or FanFiction.net.
He might have adventures where he helps dragons that are in trouble. For instance, there could be a dragon that is being held captive by dark wizards for some evil purpose. Harry, using his ability to speak to the dragon, can figure out how to free it. He could communicate with the dragon to find out where the chains are enchanted and what the weak points of the prison are.
The story would likely become more exciting. Harry could use the dragons as allies. For instance, he could ride a dragon to quickly reach places he needs to be. It would also add an element of mystery as he discovers more about the dragons' language and culture.
Well, maybe Harry discovers his ability to speak to dragons during one of his adventures in the Forbidden Forest. He could then use this ability to form an alliance with the dragons against Voldemort.
His friends would be both amazed and a bit envious. Hermione might be very interested in studying this new aspect of magic related to his ability. Ron, on the other hand, would probably be in awe and might ask Harry to use his ability to find some cool magical animals to play with. It could also make them more protective of Harry, as his ability could attract unwanted attention from those who might want to use it for bad purposes.
It can change the plot by making him an outcast among his peers. For instance, his friends might be wary of him at first.
Maybe he accidentally finds out when he is near some magnetic objects in Hogwarts. For example, he might notice that he can make the metal keys move towards him without using magic spells he already knew. It could be during a time when he is exploring an old, forgotten part of the castle where there are a lot of metal objects and strange magnetic fields.
In some fanfictions, it could be through an accidental encounter. Maybe he was in a situation where metal objects started to react to him unexpectedly, like when he was near a bunch of keys and they suddenly started to move towards him. This made him realize that he had this strange new power.
It could be that his training in magic somehow awakens his haki. As he delves deeper into advanced magic spells and combat training at Hogwarts, his body and mind start to develop this new ability. For example, during a particularly intense dueling session, he feels a strange energy coursing through him which he later realizes is haki. His professors might initially be baffled by this new power, but as he learns to control it, it becomes an asset in his battles against the forces of evil.