A great storyline might be a crossover where Danny and Robin end up in each other's universes. Danny has to deal with the more crime - filled Gotham while Robin has to handle the ghostly threats in Amity Park. This would lead to a lot of character development as they adapt to new situations.
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.
The different types of ghosts and their unique abilities and backstories add a lot of depth to the show. For example, there are ghosts with powers over time, space, and emotions, and Danny has to figure out how to defeat each of them, which often involves a lot of strategic thinking and using his own powers in creative ways.
One possible storyline could be Danny facing a new, more powerful ghost while also dealing with his regular high - school drama. In this fanfiction, the Dash x Danny aspect might add a layer of unexpected friendship or rivalry as Dash discovers Danny's secret identity and has to decide whether to support or expose him.
One interesting storyline could be where Danny and Vlad are forced to team up against a common enemy. Maybe a powerful ghost that threatens both their existences. This would put their rivalry on hold and force them to use their combined powers.
One interesting storyline could be Valerie discovers Danny's secret identity in a really unexpected way, like during a ghost attack where she's about to capture him but then realizes who he really is. It adds a whole new layer of drama to their relationship.
One interesting storyline could be Danny and Jake teaming up to fight a common supernatural enemy that neither could handle alone. For example, a powerful ancient spirit that threatens both the human and ghost worlds in Danny's case, and the magical world in Jake's. Another could be a crossover where they end up in each other's universes and have to adapt to the new rules and powers while trying to find a way back home.
Another storyline might involve Danny being wrongly accused by the Justice League of a crime he didn't commit. As he tries to prove his innocence, he uncovers a deeper conspiracy that threatens both the human world and the Ghost Zone. He has to use his wits and powers to clear his name and save the day.
Another storyline could be a 'what - if' scenario. For example, what if Sam was the one who got the ghost powers instead of Danny? This would completely change their dynamic. Sam might be more impulsive with her powers, and Danny would have to be the one to keep her in check. It could lead to a lot of interesting character development and new relationships within the story.
A really engaging storyline could be a time - travel one in Danny Phantom x Kitty fanfiction. Maybe they go back in time to prevent a disaster that would change the entire ghost - human world balance. Along the way, they learn more about each other's pasts and how their fates are intertwined. It could be full of mystery, action, and some really touching moments between the two characters.
One interesting storyline could be about Danny and the Ember family teaming up to fight a new, powerful ghostly threat. They might have to combine their unique abilities to defeat it.