Sakura could also be a potential spouse. Although she had feelings for Sasuke in the original, in fanfiction, the author could take a different route and have her end up with Naruto. Their shared experiences as teammates could form the basis of a strong relationship.
Hinata would be a very likely choice. They had a connection in the original series, and in a fanfiction, it would make sense for them to be married. Hinata's gentle nature could contrast well with Naruto's more boisterous personality.
There could even be an original character as Naruto's spouse. This would allow the writer to create a completely new dynamic. The new character could have unique abilities or a special backstory that ties in with Naruto's return and their married life together.
His wife could be Hinata. In the original series, there were hints of their relationship. Hinata has always admired Naruto and they would make a great couple. She is a strong and kind - hearted ninja from Konoha, which would make for an interesting dynamic when Naruto returns with her as his wife.
Lucy could be a potential spouse. They have a very close relationship in the original story. Maybe they got secretly married in a moment of intense emotion. It would be a big shock to their friends, but also a very interesting development as they already have such a strong bond.
The devils that oppose Rias' group could be the antagonists. They might see Naruto as an unknown threat and try to eliminate him. Also, there could be some dark magic users who don't want Naruto interfering in their plans in Rias' world.
Definitely Hinata. Her love for Naruto is well - known. Sakura, too, as she has grown closer to Naruto over the years. Ino might also be in the harem. She has had her own moments with Naruto and her skills as a ninja could be an asset. And perhaps Karui from the Cloud Village. After Naruto's peace - making efforts between the villages, she could have developed feelings for him.
Perhaps it could be someone from his own village that he never really noticed before. Like a girl who was always in the background but during his time away, she grew into a confident and beautiful woman. She could be someone who works in the hospital, and Naruto starts to see her in a new light when he comes back injured from a mission.
There could be new ninja from other hidden villages that are introduced when Naruto returns. Maybe a powerful young ninja who wants to test his skills against Naruto. Or perhaps a mysterious sage - like figure who has some connection to Naruto's new power.
There could be a powerful mentor figure that Naruto met during his time away. This person might have taught him the secrets to his newfound strength.
The fanfiction could focus on Naruto's married life in Konoha. Maybe his wife is a powerful ninja in her own right. Together, they could train the next generation of Konoha ninjas. Their relationship could be a source of inspiration for the young ninjas. Naruto's return with his wife could also bring new diplomatic relations to Konoha if his wife has connections to other villages.
Sasuke could still be a major rival. Even though they are friends, the competitive spirit between them might flare up again during the exams.
It could be a completely original goddess created by the fanfiction writer. This goddess might have unique powers like the ability to control the elements in a way different from the ninja in Naruto's world. She could be the goddess of light, for example, with the power to banish darkness and heal the sick.