One common theme is the struggle between good and evil within Danny. It often shows how his normal self battles his evil side. Another theme is the impact on his relationships. His friends and family have to deal with this new, dangerous Danny.
Another theme is the struggle between good and evil within the Danny Phantom universe. In these fanfictions, the balance is tipped towards evil, and we see how the other characters deal with that. For example, Sam and Tucker might have to find new ways to combat an evil Danny, which involves a lot of moral and ethical decisions on their part. They have to decide how far they are willing to go to save their friend and protect the town.
A common theme is the struggle between good and evil within Danny. When he's in his evil form in crossovers, it often shows the fight to bring him back to the good side.
Love and friendship are common themes. Their relationship, whether it's a budding romance or a deep platonic bond, is often explored.
One common theme is family. Since they are siblings, a lot of fanfics explore their family bond, like how they rely on each other and protect one another. Another theme is secrecy. Danny has to keep his ghost identity a secret, and Jazz often gets involved in that secrecy, either by helping him keep it or by accidentally finding out. Growth is also a theme. As the story progresses, both Danny and Jazz grow as characters, both in their personal lives and in dealing with the supernatural elements around them.
One common theme is the power struggle. Ember has her own set of powers and often tries to overpower Danny, either for her own gain or just for the fun of it. So there's a constant back - and - forth in terms of who's in control.
A very frequent theme is the idea of redemption. Some fanfictions explore whether Vlad can be redeemed through his relationship with Danny. It's about whether Danny's goodness can rub off on Vlad or if Vlad is too far gone. There's also the theme of family, as Vlad sees Danny as a sort of surrogate son, and this adds a whole layer of complexity to their interactions. They can be like a dysfunctional family, with all the drama and emotional turmoil that comes with it.
Another theme is the idea of overcoming obstacles. In a lot of these fanfictions, there are things like Danny's ghost - hunting duties or Sam's family issues that they have to get past before they can have that kiss. It adds drama and depth to the story. For example, in some, Danny has to balance his secret identity with his growing feelings for Sam, and this creates tension until they finally share the kiss.
One common theme is the relationship between Danny and Kitty. It often explores their dynamic, whether it's a budding romance or a complex friendship.
A common theme is the struggle between good and evil within Danny himself. Since Dark Danny is Danny's dark side personified, it's all about Danny facing his own inner demons. For example, in many fanfictions, Danny has to deal with the temptation to give in to the power that Dark Danny represents.
A frequently seen theme is the power of friendship evolving into love. They start as friends who understand each other's quirks and then it blossoms into something more. Also, the theme of sacrifice is there. In some fanfics, either Sam or Danny is willing to sacrifice something important, like Sam giving up some of her ideals or Danny risking his secret identity, for the sake of their relationship.