In this fanfiction, Naruto being an angel might attract the attention of some divine or otherworldly beings. So, characters like the Sage of Six Paths could play a more prominent role, guiding Naruto in his new form. Also, Naruto's sensei, Kakashi, might be involved, trying to figure out how to incorporate Naruto's angelic abilities into their battle strategies.
Obviously Naruto would be the main character as the title implies. But there could also be other characters like Sasuke who might be influenced by Naruto's angelic transformation. Sakura could also be there, perhaps helping Naruto understand and control his new angel powers.