One common theme is rebuilding. After the war, the villages, especially Konoha, need to be rebuilt both physically and socially. Another theme is reconciliation, like Sasuke coming back to Konoha and being accepted again. Healing is also a theme, as the characters have to deal with the mental and physical scars of the war.
One possible reason could be to protect his family. After the war, Naruto might have made many enemies. By faking his death, he could draw the attention of these enemies away from his family, especially his wife and children. His enemies would think he's no longer a threat and stop targeting his loved ones.
Obviously Naruto would still be one of the main characters. He played a huge part in the Fourth War and his influence would still be felt strongly in the post - war world. Sasuke would also be a main character as he was a key figure in the war as well. And Sakura, who has grown into a strong kunoichi, would also be important in the story.
Naruto is the main character, of course. Hinata is very common as she is Naruto's wife in the original series. But other characters that often show up are Temari. Since she has interacted with Naruto on various occasions and has a strong personality. Another one could be Kurenai, who, although older, could bring a different kind of maturity and wisdom to the harem dynamic in the fanfiction.
They may interact through training sessions. Naruto could be interested in learning more about Tenten's weapon - using skills, while Tenten might want to understand Naruto's chakra control better. So they exchange knowledge during their training.
Sakura would be extremely angry at first. She has known Naruto for a long time and would feel betrayed that he didn't trust her enough to tell the truth. But later, she would understand his reasons and might even help him if she could.
Their relationship could develop through shared experiences. For instance, they might volunteer together to help the orphaned children in the village. This would bring them closer as they both have a soft spot for kids. Naruto, being an orphan himself, and Hinata, who is very nurturing.
In some fanfictions, Naruto and Sasuke become closer friends. They finally understand each other completely and work together to rebuild the Hidden Leaf. They often meet up and share their experiences, training the next generation side by side.
He could start by talking to his closest friends, like Shikamaru or Sakura. They can offer him emotional support and different perspectives. Another way is to focus on the positive changes he can still make in the village, like new training programs for the young shinobi.
In a fanfic, Naruto and Tenten could become good friends. They might train together and share their experiences from the war. Naruto could inspire Tenten with his never - give - up attitude, and Tenten could show Naruto some of her unique weapon - based jutsu.