Well, in Fairy Tail Dragon Cry Nalu fanfiction, themes like friendship are quite prevalent. Since Natsu and Lucy are such good friends in the original, fanfic writers like to expand on that. Family is another theme. They create scenarios where Natsu and Lucy find a new kind of family within the guild. And of course, the theme of facing great evil together. They have to battle powerful foes and that makes for some exciting stories.
One idea could be exploring the backstory of the Dragon Cry in more detail. Maybe there was a hidden power within it that was known only to the first dragon who created it. Another could be a story where a new character discovers the Dragon Cry and has to learn how to control its power before the bad guys get their hands on it.
In a lot of these fanfictions, Acnologia is a common antagonist. He's such a powerful dragon in the Fairy Tail universe that he makes a great villain. Another one could be Zeref. His dark magic and his complex relationship with the main characters can be explored in Nalu fanfictions related to Dragon Cry.
A young dragon slayer from a far - off land who has a unique magic related to the elements that haven't been seen in Fairy Tail before. Maybe his magic is connected to some aspect of the Dragon Cry.
One idea could be that in a post - Dragon Cry adventure, Natsu and Lucy are sent on a mission to a hidden island where ancient dragon magic is said to be sealed. Along the way, they face various obstacles that test their bond, like a powerful sorcerer who tries to split them up. Another plot could involve Natsu losing his dragon slayer powers temporarily, and Lucy having to protect him while they search for a way to restore his powers using the knowledge from the Dragon Cry incident.
Their relationship could develop through shared danger. For example, if they are trapped in a magical maze as a result of the Dragon Cry's after - effects. Natsu's impulsive nature might get them into trouble, but Lucy's strategic thinking gets them out. This mutual reliance can deepen their bond. Also, if Natsu discovers a new side of Lucy, like her hidden strength or a special magical ability she has been suppressing, he may start to see her in a new light, which could lead to a more romantic development.
They can be powerful allies. Their combined dragon powers can turn the tide in battles. For instance, if one can control wind and the other can control water, they can create powerful storms to defeat enemies.
Dragon siblings in Fairy Tail fanfiction can be depicted in various ways. Some might be separated at birth and go through a long journey to reunite. Their dragon - like instincts could also influence their behavior, for example, a strong sense of territoriality or a need to hoard magical items. This makes for really interesting character development and plotlines within the fanfiction world.