A 'narusaku naruto returns fanfic' could be about many things. It might focus on Naruto's return in a scenario where he has a relationship with Sakura. It could involve adventures they go on together, how their relationship has developed during his time away and his return, and how they face new challenges in the ninja world as a couple.
You can try looking on fanfic websites such as FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of fanfictions, and there's a good chance you'll find 'narusaku naruto returns fanfic' there.
Obviously, Naruto and Sakura are the main characters. Naruto is the one who has been away and is now coming back. Sakura, being his friend and potentially more in the context of this fanfiction, is waiting for him in the village. Their relationship is a central focus, and other characters from the Naruto universe might also play supporting roles depending on the specific story.
A possible plotline could involve Naruto's return after having some sort of spiritual awakening. He returns to the village, and Sakura is the first person he seeks out. Their interactions then lead to a deeper understanding of their feelings for each other. This could involve flashbacks to their past experiences together and how those have shaped their current relationship.
The 'narusaku naruto returns from training fanfiction' could have Naruto coming back with a newfound confidence. Since he has been away for training, he might have a different perspective on things. Regarding his relationship with Sakura, he could start to see her in a new light. He may also bring back knowledge of new ninja techniques and strategies that could potentially change the way the village approaches combat and defense.
Naruto could become more mature. His time in training might have taught him patience and better control over his emotions. Sakura might also develop in response to Naruto's return. She could become more confident in their relationship, whatever it may be. And there could be changes in how other characters in the village view Naruto, seeing him as a more reliable and powerful ninja.
It could be a rogue ninja who was secretly plotting against Naruto all along. After Naruto's death, this antagonist could emerge and try to take over the village, seeing it as the perfect opportunity with the village in mourning and a bit disorganized. This ninja might have some personal vendetta against Naruto and now wants to make the village pay.
You can find 'Naruto Shippuden Narusaku fanfic' on some popular fanfic websites like Fanfiction.net. There are a large number of Naruto - related fanfics on this site, and you can easily search for Narusaku ones. Another option is Archive of Our Own (AO3). It has a great collection of fanfics, and you can filter your search specifically for Narusaku fanfics within the Naruto Shippuden category.
Perhaps in the 'naruto dies narusaku fanfic', Naruto sacrifices himself to save Sakura from a powerful enemy. Sakura, in her despair, starts to discover new aspects of Naruto she never fully realized when he was alive. She could then start a journey to find a way to bring him back, encountering many challenges along the way and meeting old friends and foes who either help or hinder her.
One great 'Naruto Shippuden Narusaku fanfic' is 'A New Beginning'. It explores their relationship post - Shippuden in a very interesting way. The author delves deep into how Sakura and Naruto's feelings for each other develop further. Another one is 'Narusaku: The Unspoken Bond'. It shows their unspoken connection and how they support each other through different challenges.