Well, perhaps in the fanfiction, Danny Phantom is on a mission to find a missing artifact that has somehow ended up in Monster High. As he explores the school, he has to deal with the various cliques of monsters. Some might be scared of him, thinking he's a dangerous spirit, while others, like Draculaura, might see him as an interesting new addition to their world.
In a 'Danny Phantom goes to Monster High' fanfiction, the plot could involve Danny being sent there to learn about different forms of 'otherness'. At Monster High, he discovers that while he's a ghost among humans, here he's just another kind of strange being. He could get involved in the school's events, like the annual Monster Ball. There, he might have to use his powers to save the day when a rogue magic spell goes wrong and threatens to turn all the monsters into stone. He forms bonds with characters like Clawdeen Wolf, who helps him navigate the social scene at Monster High.
One possible plot could be Danny Phantom accidentally getting zapped into the Monster High dimension. He might initially be confused as he tries to figure out the different rules and types of monsters there. He could make friends with some of the Monster High characters like Frankie Stein, who would be curious about his ghostly powers.
In this fanfiction, it could be that Danny Phantom meets a Danny Phantom from a parallel fan - made story. At first, they don't trust each other. But as they learn more about each other's worlds, they realize that there are some common elements that are being threatened. It could be that a powerful ghost is trying to rewrite all the fanfic universes related to Danny Phantom. So, they must combine their strengths and knowledge to stop this from happening.
Definitely Danny and Lagoona Blue. Lagoona is so laid - back and friendly, and Danny's ghostly nature would be a real novelty to her. They could have some really fun exchanges, like Danny showing her how he can phase through objects and Lagoona showing him her underwater skills.
One common theme is friendship. Characters from Danny Phantom and Monster High often form unexpected friendships in fanfiction. Another theme is the idea of being different. Both Danny, as a half - ghost, and the unique monsters in Monster High are outsiders in some ways, so this is often explored.
In 'Danny Phantom Goes to School' fanfiction, there could be a new character who is also a half - ghost and they become friends or rivals with Danny. They could team up to fight a powerful ghost that has infiltrated the school's science lab. The school setting also allows for some interesting interactions between Danny's human friends and his ghost - hunting side. For example, his friends might accidentally discover his secret identity while they are all involved in a school project.
In the fanfiction, Danny might be in the hospital because of his ghost - fighting injuries. Maybe he has to hide his ghost powers from the doctors while trying to recover.
In this fanfiction, Naruto might go to Monster High to seek some kind of special power or knowledge. He could make friends with the monster students, like Frankie Stein. Together they could face challenges like a bad guy who wants to disrupt the harmony between ninjas and monsters. Naruto would use his Rasengan while Frankie uses her electricity powers to fight the enemy.
He might meet a nurse who has some sort of psychic ability and can sense that Danny is different. This could lead to an interesting interaction where Danny has to be extra careful.
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.