In a more emotional plot, Danny has lost his family in some ghost - related incident and is all alone. Batman, seeing a kindred spirit in Danny (both having experienced loss), decides to adopt him. Danny then has to adjust to living in the Batcave and being part of Batman's crime - fighting family. He struggles with fitting in at first but eventually finds his place and becomes an important asset to the team, using his powers in ways Batman hadn't thought of before.
His ghostly wail, a very powerful attack, could be used as a last - resort weapon against powerful foes in the Batman universe. However, it also might attract unwanted attention from other supernatural entities. Danny would have to learn to control it better in the more urban and populated Gotham. This would add an interesting dynamic to the crime - fighting in Gotham as they would have to deal with the potential consequences of using such a powerful ability.
One interesting 'batman danny phantom fanfiction' could be where Danny Phantom's ghostly powers are used to help Batman in Gotham. For example, Danny could use his intangibility to sneak into places that are difficult for Batman to access and gather information.
One interesting plot could be Batman teaching Wally about stealth and detective work. Batman's dark and methodical approach would contrast with Wally's more energetic and impulsive nature.
Well, perhaps there's a plot where Jason discovers a hidden side of Gotham while under Batman's wing. He could start to form his own ideas about justice that are both influenced by Batman yet unique. For example, he might focus more on helping the poor in a different way than Batman does. This could lead to some tension and growth between them as they navigate their relationship.
One possible plot could be that Danny is kidnapped by a new ghost enemy who wants to use his powers for their own evil deeds. Maybe this enemy plans to drain Danny's ghostly energy to become more powerful. Another plot could involve Danny being kidnapped by a group of his human enemies who have finally discovered his secret identity and want to experiment on him. Or perhaps a time - traveling villain kidnaps Danny to prevent him from ever becoming a hero in the future.
Danny's powers could be a huge asset. His intangibility could help him and Batman get into places that are otherwise inaccessible. His flight would give them an edge in chasing villains across rooftops. Also, his ghostly energy blasts could be used as a new form of weapon against the bad guys in Gotham.
In some 'Batman Adopts Harry Potter' fanfictions, a great plot is when Batman tries to enroll Harry in a normal school in Gotham. Harry has to adapt to a non - magical educational system while also hiding his wizarding past. At the same time, Batman is trying to protect Harry from any threats that might come from the wizarding world, like Death Eaters or Voldemort's followers who might want to harm the Boy Who Lived.
One possible plot could be that Danny's sneeze accidentally activates a new ghost power. For example, every time he sneezes, he temporarily gains the ability to phase through different dimensions. This could lead to all sorts of adventures as he tries to control this new and unexpected power while also dealing with his regular ghost - fighting duties.
Maybe Danny and a ghost enemy are stuck together due to some strange ghostly spell. This forces them to understand each other better as they try to break the spell. As they are stuck, they start to see the other's point of view, which could lead to an unexpected friendship or at least a truce.
One possible plot could be that the evil Danny Phantom tries to manipulate Sam into helping him take over the Ghost Zone. He might use his powers to deceive her at first, but Sam gradually realizes his true intentions and has to find a way to stop him.