Perhaps the dragon in Jon's fanfiction is the last of its kind, and Jon has to protect it from those who want to harm it. There could be a whole story of them hiding, fighting off hunters, and trying to find a new place for the dragon to live safely.
In a 'Jon Snow is a Vampire' fanfiction, the plot could start with his death and subsequent resurrection as a vampire. This new form could make him an outcast, even more so than he was before. He might have to journey to find a way to reverse his condition. Along the way, he meets old friends and enemies who react differently to his vampiric state. Some might fear him, while others might see him as a powerful ally. His relationships with his Stark siblings could be severely tested as they grapple with the fact that he's no longer fully human.
One possible plot could be that Jon Snow discovers the dragon egg in a hidden place. He manages to hatch it through some unforeseen circumstances. Then, he has to keep it a secret while training it and learning to communicate with it.
One possible plotline could be that they are forced to pretend to be in a relationship for political reasons. As they act the part, they start to develop real feelings for each other and eventually share a kiss. Another could be in a post - war scenario where they find comfort in each other's arms and the kiss is a symbol of their new - found connection.
One possible plotline is that the dragon helps Harry discover a hidden magical place. Since dragons have a strong sense of magic, it could lead Harry to a place full of ancient spells or powerful artifacts.
One possible storyline is that Jon Snow uses the ice dragon to fight against the White Walkers. The ice dragon's cold breath could be a powerful weapon against the undead army. Another storyline could be that the ice dragon helps Jon Snow claim the Iron Throne. Its presence would make him a very intimidating and powerful claimant.
In this fanfiction, perhaps Peter Parker is a huge dragon fan from a young age. One day, he somehow gets transported to a world full of dragons. There, he uses his intelligence and Spider - Man - like skills to survive. He might learn how to communicate with the dragons and ends up befriending one. This dragon could then help him get back to his own world, but not before he has to face some challenges in the dragon world, like saving the dragon eggs from poachers.
Perhaps the armband is a family heirloom that Harry discovers. It could hold the key to some long - forgotten Potter family secrets. This could lead him on a journey to uncover his family's past and also give him an edge in the fight against the forces of evil. The armband might have inscriptions or symbols that he has to decipher.
One possible plotline could be that Harry discovers he has the ability to communicate with dragon serpents. This newfound skill helps him in his fight against Voldemort. Maybe the dragon serpents know of a hidden weakness of Voldemort's that no one else does.
One possible plotline could be that Luffy gets into a really tough battle against a powerful enemy that he can't defeat on his own. Dragon, being his father, senses the danger and arrives just in time. He uses his mysterious powers, like controlling the weather, to turn the tides of the battle in Luffy's favor. Then, he might give Luffy some words of wisdom about his journey and the importance of his goals before disappearing again.
One possible plotline could be that Zuko turns into a dragon to gain a new perspective on his firebending. As a dragon, he might discover ancient firebending techniques that were long forgotten. This could lead him to return to his human form with enhanced skills and a new understanding of his power. He could then use this knowledge to help his friends and bring peace to the Fire Nation.