The relationship between Naruto and Sasuke is complex. In this retrieval fanfiction, their past memories together could play a big role. Flashbacks of their time at the ninja academy, their first missions, and the bond they formed could be used to heighten the drama of Naruto's quest to bring Sasuke back.
The Naruto manga continues well beyond Sasuke's departure. It covers many significant events and character arcs that shape the overall conclusion of the series. Sasuke's leaving is just one part of the larger narrative.
One possible reason could be that Sasuke might have gone too far in his pursuit of power even after the war. He could have been a threat to the newfound peace in the ninja world, and Naruto, as the protector of peace, might have felt he had no other choice.
The relationship would evolve from a deep friendship and comradeship to a romantic partnership. They would have to be more open with each other about their feelings. Sasuke might become more protective of Naruto in a different way, not just as a friend in battle but as a future life partner. Naruto would also be more likely to confide in Sasuke about his insecurities and hopes for the future. Their bond would be strengthened further as they face the challenges of being in a relationship in the ninja world, like dealing with the opinions of other ninjas and the political implications of their union.
One possible plot could be that Sasuke gets injured during a mission and is brought to the hospital where Sakura works. Sakura then uses her medical skills to treat him, and during his recovery, they have deep conversations that rekindle their old feelings for each other.
In some fanfictions, Naruto may become more mature. After going through the arduous process of retrieving Sasuke, he realizes the complexity of relationships and the importance of his comrades more deeply. He might also become more reserved in his emotions, as the experience has made him more aware of the consequences of his actions and words.
In the hospital setting, Sasuke might initially be his aloof self. But as Sakura takes care of him or they face challenges together, he could start to open up more. For example, if Sakura is overworked, Sasuke might offer a helping hand in small ways, like getting her coffee. This would show his growing affection for her.
Sasuke's development would be complex. He might start to question his entire ideology that led him to kill Naruto. He could become more empathetic towards others as a result of his regret, realizing the value of life that Naruto always represented. He might also try to make amends in the ninja world, but it would be a long and difficult journey as he has to deal with his own guilt.
Their relationship could start with respect. Naruto has always respected Sasuke, and in this case, Fem Sasuke. After the war, they might start having conversations about their dreams for the future. This could lead to them spending more time together, like having dinners or just walking around the village. Eventually, they realize they have feelings for each other.