Well, start by having a strong concept. It could be centered around a mystery involving Shiva that ties the Naruto and DxD worlds together. Then, create believable characters, even if they are from different universes. Give them motives and personalities that are consistent. When writing the story, use dialogue effectively to show the differences in cultures and ways of thinking between the Naruto, Shiva, and DxD elements. For example, a conversation between a Naruto character and a DxD character about Shiva's significance could be really interesting. Also, be creative with the settings, combining the unique landscapes of the Naruto world, the otherworldly places in DxD, and the divine realms associated with Shiva.
In this fanfiction, Naruto's abilities would be significantly enhanced. His chakra reserves, which are already considerable as a ninja, could be limitless or close to it as the son of Shiva. He might be able to perform new jutsu that combine ninja techniques with Shiva - related powers. For instance, he could create illusions based on Hindu mythology that are not only visually deceiving but also have a spiritual impact on his opponents. His physical endurance would also be off the charts, allowing him to fight for long periods without tiring.
First, know the source materials well. Understand the rules, characters, and power systems of DxD as well as the other universe you're crossing it with. For example, if it's a crossover with Harry Potter, know how magic works in both worlds. Second, create an engaging plot. Maybe there's a threat that can only be defeated by the combined forces of both universes. Third, develop the characters well. Show how they change and adapt when exposed to a new world and new characters.
One great Highschool DxD Shiva fanfiction is 'Shiva's Heir'. It explores the idea of a new character being related to Shiva and their adventures in the DxD universe. It has a really interesting plot with lots of action and character development.
The plot could involve Naruto being an outcast in the DxD world at first because of his strange origin as the son of Shiva. But then, as he shows his strength and determination, he gradually earns the respect of the various factions. He could introduce some ninja concepts like shadow clones to the DxD characters, which they could use in their battles. And his connection to Shiva might give him some divine powers that are both a boon and a burden as he tries to find his place in this new world.
One interesting concept could be the combination of different power systems. For example, how the ninjutsu from Naruto might interact with the magic in DxD. Maybe a character could use shadow clones to perform a complex magic spell simultaneously. Another concept could be the crossovers of characters. Picture Naruto characters in the DxD world, like Naruto himself being in the middle of a devil - angel - fallen angel conflict. It could lead to really unique story developments.
First, you need to study the source materials well. Know the characteristics of Shinso vampires and the world of DxD. This way, you can create a story that fits within the existing framework.
To write a good Naruto x Highschool DxD fanfic, you need to focus on the character interactions. How would Naruto react to the flirty nature of some Highschool DxD characters? How would the devils view Naruto's strong sense of justice? Also, build a believable world. Since it's a crossover, you have to make it seem like these two very different worlds can co - exist. You can do this by creating a common threat or goal. And don't forget about the pacing. Keep the story moving at a good speed, not too slow or too fast. Throw in some action scenes, but also have some quiet moments for character development.
To write a good fanfiction, you should also focus on the pacing. Don't rush through the story. Build up the plot gradually, introduce new elements and conflicts at a reasonable pace. For example, if you're introducing a new villain, show their power and motives bit by bit. Also, good grammar and spelling are important. It makes the reading experience much smoother. And don't be afraid to add your own creativity. Maybe create a new power or a new type of character that fits within the universes of the two series.
First, know the Naruto universe well. This includes understanding the characters, their personalities, and their abilities. For example, Naruto is known for his determination and his powerful jutsu. Then, come up with an original idea. It could be a new adventure for Naruto or a different take on an existing event. Also, good grammar and spelling are important to make the story readable.
First, know the lore of Highschool DxD well. This includes understanding the different types of devils, their powers, and the hierarchy in the devil world. For stray devils specifically, study their characteristics and how they are different from regular devils. Second, create interesting characters. Make your stray devil character have a unique backstory, personality, and motivation. It could be something like they were cast out from the devil community for a specific reason and now they are trying to find their place. Third, have a good plot. Maybe start with a problem that the stray devil faces, like being hunted by other devils or having to solve a mystery related to their past.