Obviously, Naruto and Sasuke are the main characters. Naruto is the one on the mission to retrieve Sasuke, so he will be at the forefront of the story.
Another character could be Sakura. Since she has her own feelings for Sasuke, she might be involved in the fanfic as well. She could either be helping Naruto from the side or even be part of the retrieval team. Her presence can add more emotional depth to the story as she has her own complex relationship with Sasuke.
A crucial element is the conflict. There's the obvious external conflict of having to fight Sasuke's pursuers or those who want to stop Naruto. But there's also internal conflict within Naruto. He may doubt himself, or struggle with his feelings towards Sasuke. This internal conflict can drive the story forward and make the character more relatable.
Obviously, Naruto and Sasuke are going to be the main characters. Their relationship and how it develops after their fight is likely to be the central focus of the fanfic.
In some 'naruto retrieves sasuke fanfic', there could be a plot where Sasuke himself is in a moral dilemma. He might not be fully against being retrieved, but his pride and his own goals are holding him back, adding an interesting layer to Naruto's mission.
Well, obviously Naruto and Sasuke are the main ones. Since it's about Naruto absorbing Sasuke, their relationship is at the core. But also, characters like Kakashi could be involved. He might be the one guiding Naruto on how to control his new powers or trying to understand the implications of this strange occurrence.
Well, obviously Naruto himself would be the main character. There could also be his friends like Sasuke and Sakura, who might be involved in the interactions between the two Narutos. Maybe they are confused at first by seeing two Narutos, but then they help them figure out what's going on.
It could still be Naruto himself. Since he's the central character in the original series, many fanfics would likely continue to build on his story.
Obviously, Naruto would be one of the main characters as the story is about him being the son of Whitebeard. Whitebeard himself would also be a major character, even if he might not be around for the whole story. And then there would be the other members of the Whitebeard pirates, like Marco. They would play important roles in Naruto's life in the pirate world, either as mentors or comrades.
Obviously, Naruto and Jiraiya are the main characters. They are the focus of the 'naruto meets jiraiya' concept. Naruto, the energetic and determined ninja, and Jiraiya, the wise and powerful mentor.
Naruto is surely going to be one of the main characters. After all, it's a Naruto fanfic. Sasuke is also very likely to be there as his rival and friend. Sakura might also play an important role.
Naruto himself would probably be one of the main characters. Since he has always been about protecting his friends and the village, a 'greater good' narrative could put him in situations where he has to make even more difficult decisions regarding the well - being of everyone. He might have to sacrifice his own desires for the greater good.