One interesting fanfiction could be where Danny has to face a powerful ghost on his Deathday that has a personal vendetta against him. This ghost might use the special energy of the Deathday to its advantage, creating a really intense battle for Danny.
There might be a fanfiction where Danny's friends plan a special celebration for his Deathday, not realizing the significance and danger it holds in the ghost world. So, they end up putting Danny in more danger as their celebration attracts unwanted ghostly attention. But in the end, Danny manages to protect them and learn more about the nature of his Deathday.
I'm not sure of a specific one off the top of my head, but you can try looking on fanfiction websites like Archive of Our Own. Just search for 'Danny Phantom Deathday' and you'll likely find a bunch of different stories. Some might focus on the emotional side of Danny dealing with the anniversary of his death, while others could be more action - packed with ghost battles.
One interesting story could be about Danny and Sam going on a ghost - hunting adventure together. They might discover a new type of ghost that has unique powers and they have to figure out how to defeat it using their combined skills.
One interesting storyline could be Paulina finally realizing Danny Phantom and Danny Fenton are the same person. She could initially be shocked but then come to accept it and they team up to fight a new powerful ghost. It would add a whole new dynamic to their relationship.
One interesting story could be Danny's first encounter with a powerful ghost. He was probably really scared but managed to use his newfound powers in a creative way to fend it off. It showed his growth from an ordinary teen to a hero.
One interesting Danny and Dani fanfiction could be about them teaming up to fight a new and powerful ghost. They use their combined powers and unique abilities to outwit the enemy. For example, Dani might use her speed while Danny uses his more powerful ghost ray.
Another type of interesting fanfiction in the Danny Phantom universe might be those that delve into his relationships. It could be his friendship with Sam and Tucker taken to new levels. Maybe they go on an adventure together that tests their friendship in ways not seen in the original series. For instance, they might have to make a difficult choice between saving Danny's secret identity or saving the town from a new ghost threat.
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.
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.
One idea could be exploring Danny's relationships in a different way. For example, how his friendship with Sam and Tucker might develop if they faced a new supernatural threat. Another could be a story where Danny discovers a new power and has to learn to control it while dealing with school and his ghost - fighting duties. And perhaps a fanfiction where Danny travels to an alternate dimension within the Danny Phantom universe.
One interesting danny phantom lemon fanfiction could be about Danny's new ghostly power discovery within the context of a unique adventure. Maybe he uses it to save his friends in a very unexpected way.