Another possibility for main characters could be Kakashi from Naruto and Toph from Avatar. Kakashi's wisdom and experience as a ninja could be valuable in the Avatar world. Toph, on the other hand, with her unique earthbending skills and no - nonsense attitude, could offer a different perspective. They could form an unlikely duo, with Kakashi learning about earthbending from Toph and Toph being intrigued by Kakashi's Sharingan and ninjutsu techniques.
Well, it could be a story where the ninjas from Naruto learn about bending in the Avatar world. They might be initially confused but then start to adapt. Naruto himself could try to learn airbending, given his fast - moving and free - spirited nature. And there could be a conflict where the shinobi way and the bender's philosophy clash, leading to interesting character developments.
Toph would be an important character. Her earth - bending skills and no - nonsense attitude would be valuable in the post - war world. She could help with rebuilding efforts, especially in the Earth Kingdom. Sokka, with his strategic mind, would be another likely main character. He could be involved in diplomatic negotiations and helping to plan for the future security of the nations. And of course, there could be new characters introduced who are the children or students of the original heroes, bringing in a new generation's perspective.
There could also be some original female characters created specifically for the fanfiction. Maybe a female fire - bender who has a secret past and sees something in Naruto that makes her want to open up. She could be part of the harem, adding her own unique story and relationship with Naruto to the mix.
In the Avatar world, Katara could be one of the potential characters. She is strong - willed and caring, and might be attracted to Naruto's determination. Toph could also be a part of it. Her tough - as - nails attitude might find Naruto's unique powers interesting.
Obviously Naruto would be one of the main characters as the title implies he's the emperor. Another could be Sasuke. He might be Naruto's right - hand man or sometimes a rival within the new empire. From the Avatar world, Aang could be a major character. He could either be an ally or someone who initially doubts Naruto's rule but later comes to respect him.
Maybe the main antagonist is a corrupted military leader in the Metro Last Light world. He sees Naruto as a threat to his power and control. He starts a war against Naruto and the people who side with him. He uses his military resources and knowledge of the metro layout to try and defeat Naruto, much like how Orochimaru was a constant threat to Naruto in his own world.
Sakura from Naruto is often included in these crossovers as well. Her skills as a healer and her growth as a strong female character can add depth to the crossover stories. She could potentially learn new forms of healing from the Avatar world or teach her own medical ninjutsu to Avatar characters.
Obviously Naruto and Wolverine could be main characters. Wolverine's tough - guy attitude and his healing factor would contrast well with Naruto's upbeat and determined personality. Jean Grey could also be a main character. Her powerful telepathic and telekinetic abilities would be interesting to see in the Naruto world, especially when interacting with ninjas who rely on physical and chakra - based skills.
Obviously Naruto would be one of the main characters. He could bring his unique ninja abilities and his indomitable spirit to the Titanfall universe. Another main character could be a Pilot, maybe a young and inexperienced one who Naruto befriends and helps grow. And a Titan itself could also be considered a main character in a way, as it has its own personality and capabilities that interact with Naruto and the Pilot.
It could be a rogue ninja who has somehow harnessed the power of the Crimson Avatar in a dark and corrupted way. This ninja could use his powers to try and take over the ninja villages, believing that the traditional ninja ways are weak. He might see himself as a new kind of leader, using fear and his overwhelming Crimson Avatar powers to rule.