Obviously, Naruto and Karin are the main characters. Naruto, the hero of the Hidden Leaf Village, and Karin, who has her own set of abilities and a history. In this fanfiction, they will probably be put in various situations together that will explore their characters more deeply. For example, Naruto's optimistic nature might contrast with Karin's more cynical side at first, but as the story progresses, they will influence each other.
One possible plot could be that Naruto and Karin are on a mission together in a new, uncharted land. Along the way, they face many challenges that force them to rely on each other. As they spend more time together, they start to understand each other's pasts and develop a deeper bond.
Obviously, Naruto and Karin are the main characters. Naruto is the main protagonist of the Naruto series, and Karin is a character who has a connection to him. In fanfics, their relationship, whether it's friendship, rivalry, or something more, is often explored.
Since it's a fanfic, it could vary. But most likely Naruto would be one of the main characters, as the title has 'naruto' in it. There could also be Sasuke, as he has a complex relationship with Naruto in the original series. Sakura might also be involved as she is part of their team.
Sasuke, who has been on a journey of revenge and self - discovery for a long time, and Karin, who has had her own experiences and feelings for Sasuke. Their personalities will play a big role in how they handle the situation of the pregnancy. For example, Sasuke's brooding nature might make him initially hesitant, while Karin's loyalty and determination could drive her to be more positive about it.
The main characters are obviously Karin and Toshiro. Karin is often portrayed as a strong - willed character with her own set of abilities. Toshiro, on the other hand, has his own unique powers and personality. And of course, the baby is also an important character in this fanfiction, even if it may not be as fully developed as the other two at the start.
Naruto, having been banished, may initially lose his sense of purpose. However, with Karin by his side, he could find a new reason to strive. He might develop a more nuanced view of the ninja world and its politics. Karin, on the other hand, could develop a softer side. She has always been in a tough situation, but Naruto's kindness could make her more empathetic. She may also start to trust others more, especially Naruto, which is a big step for her character.
Sasuke could also be an important character in this type of fanfiction. His relationship with Karin, whether it's a friendship, a rivalry or something more complex, can add depth to the story. Also, his own goals and powers might interact with Karin's Uzumaki - related activities. For instance, if Karin is trying to revive the Uzumaki clan's power, Sasuke might be interested in that power for his own reasons, like using it to fight against the enemies of the Hidden Leaf Village.
Sakura could be one of the characters. Since she has a long - standing relationship with Naruto, she might be part of this harem - like situation. Her medical skills could also complement Naruto's abilities. Another could be Hinata. Her gentle and loving nature towards Naruto would fit well in this scenario.
Well, Karin is for sure a main character as she is taking over Sakura's position. Sakura, although being replaced, still has an important role as the benchmark for Karin's replacement. Then, other characters in their shared universe who interact with either of them could be main characters too. For instance, Naruto could be involved, seeing as he is friends with Sakura and may have some sort of reaction to Karin replacing her. Also, characters from their respective teams or groups might be main characters as they would be affected by this replacement.
I'm not sure specifically as there could be many different 'Lean on Me' real stories. But generally, it could be a person in need and those who offer support like friends or family members.