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 a 'Bruce Wayne adopts Danny Phantom' fanfiction, Danny's powers would have a profound impact on the Batman universe. His power of overshadowing, where he can take control of someone's body, could be a very useful tool in certain situations, but also a dangerous one if misused. His ecto - plasm based powers could be studied by Bruce to develop new technologies for fighting crime. Also, Danny's connection to the Ghost Zone could introduce new dimensions and enemies to the Batman lore, making Gotham's underworld even more complex and dangerous.
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.
In this fanfiction, perhaps Danny Phantom's identity gets exposed in his hometown in a way that makes it unsafe for him. Bruce Wayne, who is always on the lookout for those in need, decides to adopt Danny. Danny brings his unique perspective and powers into Bruce's world. He might start training with Bruce and the Bat - family, all while trying to keep his ghost - related problems from spilling over into Gotham's normal world.
His powers might also make Jason more protective. Knowing that Danny is different and has these abilities that could be exploited, Jason would be extra vigilant. This could lead to some arguments as Danny might feel smothered at times, but overall it would show how much Jason cares about him and is willing to go to great lengths to keep him out of harm's way.
His powers could become more ice - based. Instead of the normal greenish - blue energy, his blasts might turn a frosty white. His ability to fly could also be affected, with a cold trail following him as he moves through the air.
In Danny Phantom fanfiction, heat might affect Danny in various ways. For example, his ghost powers could be weakened as some fanfics might play with the idea that extreme conditions like heat disrupt the balance of his human - ghost hybrid state. It could also make it harder for him to stay invisible or intangible as his energy is being sapped by the heat.
The Joker would probably be both intrigued and excited. He might see Danny's powers as a new and interesting toy to play with. He could try to find ways to manipulate Danny into using his powers for the Joker's own chaotic purposes. For example, he might trick Danny into using his intangibility to break into a high - security building so the Joker can plant some crazy bombs or something.
There could be a connection in terms of the themes they both explore. Danny Phantom often deals with themes of identity and using one's powers for good, and Batman is all about Bruce Wayne's dual identity and his fight for justice. A fanfiction writer might see these similarities and decide to blend the two, perhaps having Danny learn something from Batman's sense of justice or vice versa.
His invisibility power would be extremely useful for stealth missions in RWBY. He could easily sneak up on Grimm or gather intelligence without being detected.
Well, in certain fanfictions, Danny's power of flight could be revealed to be much more than just floating in the air. It could be related to his emotional state. For example, when he's extremely determined or angry, his flight becomes faster and more powerful. This shows that his powers are not only physical but also tied to his emotions.
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.