Perhaps in this '10 Years Later' fanfiction, Danny has become a sort of legend in the world. He has to deal with younger generations of ghosts and humans who either idolize him or are skeptical of his methods. There could be a new villain who is aware of Danny's past and tries to use it against him. Danny may also be exploring new aspects of his powers that he didn't know about before, like the ability to travel to different dimensions related to the ghost zone.
Obviously Danny Phantom himself would still be a main character. His friends like Sam and Tucker would likely also be important. They've probably grown and developed new skills over the 10 years.
The plot could be centered around a mystery. A strange series of events start happening in Amity Park and it seems to be related to some new technology that Dr. Drakken has created. Danny Phantom investigates and runs into Shego. They start off as adversaries but as they dig deeper, they realize they need to work together to solve the mystery. Maybe there's a hidden force that is using Drakken's tech to open portals to the Ghost Zone and release dangerous ghosts, and only Danny and Shego can stop it.
Well, in the 'danny phantom is a lion fanfiction', it could be that Danny is cursed to become a lion at times. As a lion, he discovers new aspects of the ghost world. For example, there could be a group of lion - like ghosts that only communicate with him when he's in lion form, and they tell him secrets about his powers or his family's past that he didn't know before.
One possible plot could be that Izuku discovers the existence of Danny Phantom through some kind of interdimensional event. He then tries to learn from Danny's way of handling his powers and his secret identity, applying those lessons to his own journey as a hero in training.
A possible plot could be that Maddie is trying to create a device that can communicate with ghosts in a more peaceful way. Danny, being half - ghost, is both excited and a bit worried about this. Lemon, who has a more open - minded view on the supernatural, encourages Maddie. Danny then gets involved in the project, and they face many challenges along the way. For example, some other ghosts might not want humans to be able to communicate with them so easily, and they try to stop the project. This could lead to a story full of drama, with Danny having to use his powers to protect Maddie and Lemon while also trying to support Maddie's scientific goals.
The plot could involve some sort of mystery related to the pregnancy. Like, there could be a ghostly force that is either helping or hindering the pregnancy. And they have to figure out what it is and how to deal with it. Also, their friends like Tucker could play important roles in supporting them.
Maybe Danny's parents die in a ghost - related accident and he's left alone in the ghost zone. Kitty, having a soft spot for the young half - ghost, takes him in. She has to protect him from other ghosts who see Danny as a threat or a novelty. As Danny grows, he starts to question Kitty's more devious ways of dealing with problems in the ghost zone and tries to find his own path while still respecting her as his caretaker.
If Danny Phantom is adopted by Flash in fanfiction, it could completely change Danny's life. He would be exposed to a whole new set of allies and enemies. For example, he might have to face off against Flash's villains, like Reverse - Flash. At the same time, he could also form new friendships with Flash's friends, like Iris. Danny's powers, which are more supernatural in nature, could be a source of fascination and also a bit of confusion for the Flash and his team. And Danny would have to adapt to living in a world where speed is the most prominent power, which is very different from his own world where his ghost powers set him apart.
The plot of 'Danny Phantom Betrayed Lemon' fanfiction might involve Danny being forced to betray someone against his will. Maybe he's under a spell or some form of mind control. The 'lemon' aspect could be related to how this betrayal leaves a sour taste in the mouths of the other characters. They might struggle to come to terms with what Danny has done, and there could be a long journey of forgiveness or revenge in the story.
A plot might be that Dora is on an adventure in a spooky forest when she accidentally crosses over into Danny's world. Danny, thinking she's a new kind of ghost at first, tries to capture her. But then they realize they are both in a strange situation. They decide to team up to find a way for Dora to get back home. During their journey, they encounter other ghosts and obstacles, and Danny has to protect Dora while she uses her wits to solve some of the puzzles they come across. Their friendship blossoms as they face these challenges together.