I think Kakashi from Naruto would be really cool in a fanfiction with Asura's Wrath. His calm and collected nature, along with his Sharingan abilities, could provide some strategic advantages in battles against the powerful foes from Asura's Wrath. Also, Yasha from Asura's Wrath with his loyalty to Asura and his combat experience would be a great character to include for some intense action scenes.
A really interesting crossover idea could be a tournament - style story. Characters from both Asura Wrath and Naruto universes are gathered to compete in a tournament. This would allow for all kinds of match - ups. For example, Rock Lee's taijutsu skills against an Asura Wrath character who is also a melee combat expert. It would be exciting to see who would win and how they would adapt their fighting styles.
Asura is surely a main character in this fanfic. Besides, characters like Piccolo could also be important. Piccolo is a powerful and intelligent character in the DBZ universe. He might play a role in dealing with Asura's wrath, either as an ally or an adversary depending on how the story unfolds. Also, there's a good chance that other Saiyans like Gohan could be main characters as well, since they are key figures in the DBZ world and their reactions to Asura would be interesting to explore.
The Sage of Six Paths could be included. As he is the originator of many ninja powers, his connection to Amaterasu could be explored. Maybe he had a hand in creating or containing the power. His presence in the fanfiction would raise the stakes and give a more epic feel. Additionally, Hinata could be in the story. Her love for Naruto could play a role, for example, if Naruto is in danger because of Amaterasu, Hinata could try to save him in her own way.
Sasuke is a great character to include. His cool and brooding personality can create interesting dynamics in crossovers. For example, if he crosses over into the world of Attack on Titan, his skills as a ninja would be put to the test against the Titans. Another interesting character is Kakashi. His laid - back yet highly skilled nature can add humor and action to crossovers. He could be a great addition in a crossover with the world of Inuyasha, sharing his knowledge of combat and jutsu.
One way to blend the worlds is through the concept of power. Asura Wrath has incredibly powerful and god - like beings. In a fanfic, you could have Naruto characters encounter these powerful entities. For example, Naruto himself could meet Asura and learn about a different kind of chakra or power source. This would not only introduce a new element to the Naruto world but also create an interesting dynamic as Naruto's ideology of never giving up might be put to the test against the seemingly invincible Asura.
Asura and Shepard would be really interesting. Shepard is used to leading and making tough decisions, while Asura is driven by his wrath. Their different personalities would create a lot of tension and also great moments of cooperation. For example, when facing a tough battle, Shepard might try to come up with a strategic plan, but Asura could just charge in with his brute force. They would have to learn to work together.
Eärendil is quite an interesting character. His journey to seek help against Morgoth and his role in the war are full of potential for creative writing. Another is Fingolfin. His courage in facing Morgoth one - on - one is a great aspect to explore. And then there's Melian, the Maia. Her powers and her influence on Doriath during the war can make for very engaging stories.
Another unexpected pairing would be Asura and the Flash. The Flash is so fast and relies on his speed and quick thinking, while Asura is more about raw power. The Flash could try to outmaneuver Asura, but Asura's power might be too much. However, if they could find a way to work together, they could be a very effective team. For example, the Flash could lead enemies into Asura's path for him to smash.
One of the most interesting characters to include is Nagato. His Rinnegan abilities and his connection to the Sage of Six Paths can create some really complex and exciting storylines in a Sennin Naruto fanfic. He could have some sort of interaction with Naruto's Sage Mode, perhaps teaching Naruto something new about the power of the Sages. Additionally, characters like Gaara can be interesting. His relationship with Naruto and his own unique powers can be incorporated into the fanfic in relation to Naruto's Sage Mode journey.
I think Kiba and Akamaru would be really fun to include. Kiba's boisterous nature could create some comical moments during the wedding preparations or at the wedding itself. Akamaru could also be part of some cute interactions with Naruto and Fuu. Tsunade would also be an important character. As the Hokage, she could have some say in the marriage, or at least offer her wisdom and support to Naruto. And Rock Lee could be there, showing off his crazy training regime and giving Naruto some motivation for his new married life.