Perhaps the relationships in the story are changed. His friendships with Sasuke, Sakura, and others might be altered. He could return and find that his friends have grown in unexpected ways, leading to new dynamics between them.
His character might become more mature. He has seen more of the world outside Konoha, so he could be more understanding and patient. For example, he might not be as quick to get angry at the villagers who once shunned him.
The fanfiction may change the pacing. In the original Naruto, there are specific story arcs and build - ups. However, 'naruto returns changed' might speed up or slow down certain parts. Maybe his return is rushed in the fanfiction, or there are more flashbacks and introspection compared to the original.
Another possible plot point is that Naruto's return changes the political situation in Konoha. He could have different ideas about how the village should be run after seeing other places. He might challenge the existing council or propose new policies for the ninja academy to improve the training of young ninjas. His influence could also extend to the relationships between different ninja clans in Konoha, either strengthening or straining them depending on the nature of his changes.
In some fanfictions, Naruto might return to Konoha to a cold reception because the villagers still hold grudges from his past. Maybe they haven't fully accepted his power or the chaos he sometimes brought. For example, they could be afraid of his Nine - Tails power flaring up again and causing destruction.
In this fanfiction, the plot might involve Kushina coming back to help Naruto in his toughest battles. Maybe she uses her unique chakra abilities that Naruto has inherited to give him an edge. She could also provide emotional support, as Naruto has always longed for his mother.
Another theme is growth. Both Naruto and Hinata may have grown separately during Naruto's absence. When he returns, they have to adjust to the new versions of each other. For instance, Hinata might have become stronger in her own way, and Naruto has to recognize that.
Obviously, Kushina is one of the main characters. Naruto is also a central figure as her son. Since it's related to the Naruto universe, characters like Sasuke, Sakura, Kakashi might also be important in the fanfiction. They could interact with Kushina in various ways, like Sasuke might be skeptical of her at first, or Sakura could be eager to learn from her.
In such a fanfiction, Naruto might return to Sakura with newfound powers. Maybe he comes back after a long and dangerous mission. He could finally confess his long - hidden feelings for Sakura, leading to a romantic reunion.
One possible plot could be that Naruto has been on a long and secret mission. During this time, he met someone and had a child. Now he returns to the village with the child, and the villagers are both shocked and curious. His friends, like Sasuke, might be initially skeptical but then come to accept the new situation. The child could also have some unique powers inherited from Naruto, which could lead to various adventures as they try to figure out how to control and develop these powers.