The relationship between Naruto and Lavi would be quite fun. Lavi is a bit of a joker and Naruto's positive attitude would match well with him. They could team up and get into all sorts of adventures. Hinata might be a bit shy around some of the D Gray - Man characters at first, but she would gradually open up. The relationship between the Akatsuki and the Akuma would be very different. The Akatsuki are more about power and their own goals, while the Akuma are mindless servants of the Millennium Earl. However, some members of the Akatsuki might see the potential in using Akuma for their own ends, which would create a very dangerous situation for both worlds.
One possible scenario in this crossover fanfiction could be the characters from D Gray - Man having to adapt to the unique supernatural environment of High School DxD. For example, Allen Walker might find himself in the middle of a battle between devils and angels in the High School DxD world. His Innocence could be perceived in different ways by the various factions there.
One idea could be that the Akatsuki from Naruto are somehow connected to the Noah family in D Gray - Man. Maybe they are both after a powerful and ancient artifact that has the power to change both worlds. Another plot could involve Naruto characters having to deal with Innocence and Akuma in the D Gray - Man universe. For example, Naruto's chakra could be seen as a similar power source to Innocence and he has to learn how to use it to fight the Akuma.
A crossover with Fullmetal Alchemist could also be fascinating. Picture Edward Elric and the D Gray - Man characters collaborating to understand the mysteries of the Gate and the Innocence. Maybe they find out that there are connections between the two in terms of the source of power and the balance of the world. They could also face off against enemies that are a combination of Homunculi and Akuma.
In 'naruto d gray man fanfiction', the settings are combined in unique ways. The dark and gothic world of D.Gray - Man and the more traditional ninja world of Naruto come together. This can lead to really creative descriptions of new places. Moreover, the fanfiction can play with the moral and ethical concepts from both series. For example, how the concept of 'good' and 'evil' in Naruto compares to that in D.Gray - Man when the two worlds collide.
Well, 'Naruto and D Gray - Man: Fusion of Worlds' is another one. It often delves into how the different magic systems and ninja techniques could co - exist. It might show how Allen Walker's Innocence could interact with Naruto's chakra, leading to some really creative and exciting plot developments.
The exploration of different cultures within the two series is also a theme. Naruto has its ninja culture with clans and jutsus, while D Gray - Man has the religious - inspired elements of the Black Order and the concept of the Innocence. Fanfics might show how the characters from one culture react to the other, and how they can learn from each other's values and ways of life.
Well, it's the novelty. Combining Allen from D.Gray - man with other universes or stories creates new and unexpected situations. It allows fans to see their favorite character in different lights.
One idea could be to have characters from 'D Gray - Man' interact with characters from another series in a post - apocalyptic setting. For example, they could team up to fight against a new type of Akuma that has emerged due to the crossover's unique circumstances.
One idea could be that the characters from 'Bleach' and 'D.Gray - Man' are brought together to fight a common enemy that is a fusion of Hollows and Akuma. For example, Ichigo and Allen could team up, with Ichigo's powerful Zangetsu and Allen's Innocence combining their powers in unique ways to defeat this new threat.