Well, perhaps he could use his new dragon form to fight against Voldemort in a very unexpected way. He might be able to breathe fire on the Death Eaters and protect Hogwarts more effectively.
In this fanfiction, it might be that a new and mysterious potion was accidentally spilled on Harry. As a child, he'd be super cute and all his friends would be really confused. Hermione would probably immediately start researching ways to reverse the spell. Ron, on the other hand, would be a bit more clumsy in dealing with this new young Harry. And Harry himself might have a lot of fun exploring Hogwarts in a new way, with the perspective of a child but the knowledge of an older wizard.
One possible plot could be that the dragon is a gift from a mysterious wizard. Harry at first is hesitant but soon grows attached to it. The dragon has special powers that draw the attention of both the good and bad in the wizarding world. Harry has to train the dragon and at the same time, deal with the political implications of having such a powerful creature. His friends are both in awe and a bit scared of the dragon, which also creates some tension in their relationships. And as the story progresses, the dragon becomes a key factor in a major battle against dark forces.
One possible plot could be that a dark wizard uses a powerful and forbidden spell on Harry. This spell alters his very essence and turns him into a weapon. He then becomes a tool in the dark wizard's hands to attack Hogwarts. But his friends, like Hermione and Ron, notice the change and try to find a way to reverse the spell. They search through ancient books in the restricted section of the library and finally discover a counter - spell.
In the fanfiction, Harry might be cursed to transform into a dragon periodically. He then has to figure out how to control this new form. He could meet other magical creatures that are either scared of him or intrigued by his dragon form. He might also find that his dragon form gives him unique powers that he didn't have as a human wizard, like the ability to fly faster or breathe a more powerful type of fire.
One possible plot could be that Harry is under a powerful dark spell. The transformation into a dragon might be a part of a scheme by Voldemort or his followers to either discredit Harry or use his new form for some evil purpose. Maybe Harry has to learn to control his dragon form in order to fight back and protect Hogwarts and his friends.
Well, perhaps in this fanfiction, Harry Potter discovers he has some sort of divine connection to the dragon god. Maybe he gains the ability to communicate with dragons and uses their powers to fight against Voldemort. He could also be on a quest to understand the nature of this newfound connection and how it relates to the wizarding world.
In such a fanfiction, perhaps Harry discovers a dragon in the Forbidden Forest. He realizes the dragon is being hunted by dark wizards. Harry, using his skills and magic, decides to protect the dragon. They form a bond as Harry spends time understanding the dragon's needs and communicating with it through magic. Eventually, the dragon becomes his ally in fighting against the dark forces in Hogwarts.
One possible plot could be that Harry has to keep his true dragon form a secret while at Hogwarts. He might face challenges like controlling his dragon instincts during classes or Quidditch games. For example, his natural inclination to hoard things could get him into trouble in the common room when he tries to stash away everyone's shiny objects.
Well, perhaps the plot could involve Harry finding a dragon egg and raising the dragon as his familiar. This would bring a whole new set of adventures as he has to hide the dragon from the Hogwarts faculty who might not be too keen on a dragon on campus. He could also use the dragon's special abilities to his advantage in his battles against Voldemort.
Well, perhaps Harry could discover he has some dragon - like abilities. Maybe he can breathe a bit of fire when he's extremely angry. It would make him even more of an outcast at first, but then these abilities could help him in battles against Voldemort.