One idea could be that Danny and Blackfire meet during a space - time rift accident. Danny is on a mission to close the rift when he encounters Blackfire, who is escaping from some intergalactic bounty hunters. They have to team up to fend off the hunters and in the process, learn about each other's powers and worlds.
Maybe Blackfire ends up on Earth in Amity Park by mistake. She crosses paths with Danny, who initially mistakes her for a new ghost threat. But as they interact, they realize they both have a lot in common in terms of being outsiders in their own ways. They could then form an unlikely friendship and help each other with their respective problems.
A plot could involve Blackfire being hired by a powerful villain to capture Danny for his unique ghost powers. However, during her attempts, she starts to question the motives of the villain. Danny, on the other hand, tries to convince her to switch sides, and through a series of events, they end up working together against the real bad guy.
One idea could be that Danny discovers a new ghostly power that he uses to take revenge on a group of bullies who have been tormenting his friends. He could use his intangibility in a creative way, like sneaking into their lockers and making their things disappear.
One idea could be Danny Fenton having to deal with a new ghostly enemy that can manipulate time, making his double life as Danny Phantom even more chaotic. Another could be Danny trying to balance his high school life, including exams and relationships, while also facing a ghost invasion that only he as Danny Phantom can stop. Or perhaps a story where Danny Phantom discovers a hidden power within himself that has a connection to his human side, Danny Fenton.
One idea could be that Danny gets an illness that affects his ghost powers. For example, he might start losing control over his intangibility or invisibility. This could lead to some really comical or dangerous situations. Another idea is that his friends try to find a cure for his strange ghost - related illness while also keeping it a secret from the town.
Well, here's a plot. In a strange turn of events, Danny's ghost powers start to interact with alicorn magic in unexpected ways. This causes chaos in both worlds. The alicorn and Danny must work together to figure out how to stop the strange energy fluctuations. They might have to travel to different dimensions within their universes to find a solution. Along the way, they meet other characters from both franchises who either help or hinder their progress.
One idea could be that Danny is experimented on by a new group of ghost hunters who want to find a way to permanently strip him of his powers. They use some high - tech equipment that has unforeseen effects on his ghostly half, causing him to have strange new abilities. Another could be an experiment gone wrong in the Ghost Zone that Danny has to deal with the consequences of, like accidentally creating a new type of ghost. Maybe Danny himself decides to conduct an experiment to see if he can control his transformation better, but it backfires and he gets stuck in his ghost form for a while.
One idea could be that the twin has a different set of powers. For example, while Danny can go intangible and invisible, the twin might have the power to control time on a small scale. This would create interesting scenarios where they have to work together, like when Danny is in a tough fight and the twin uses time - control to give him an edge.
Well, perhaps in the fanfiction, Undergrowth could create a parallel dimension filled with his overgrown plants and trap Danny there. Danny then has to navigate this strange new world, make allies among the plant - like creatures that are also being oppressed by Undergrowth, and find a way to break out and stop Undergrowth from spreading to the real world. This would be an exciting adventure full of mystery and discovery for Danny.
One idea could be that Rouge discovers Danny's secret identity and tries to use it to her advantage in some way, like getting information from the Ghost Zone. Another could be a team - up where they have to face a common enemy that is causing chaos in both the human world and the world Rouge is familiar with.
A cool plot for Danny Phantom Rebirth fanfiction might be Danny traveling to a different dimension where the rules of the ghost world are completely different. He could meet alternate versions of his friends and enemies. Maybe in this dimension, ghosts are the rulers and humans are the ones with special powers to fight back. Danny would have to adapt quickly and find a way to get back to his own dimension while also learning valuable lessons about his powers and responsibilities.
One idea could be that Danielle tries to fit into Danny's normal life at school without revealing her powers. She could struggle with making friends and dealing with the normal teenage drama while also having to hide her true identity. Another plot could be Danny and Danielle teaming up to fight a new powerful ghost that is causing chaos in the town. They might have to combine their powers in a new and unique way to defeat it.