Naruto could be one of his allies. Naruto has this knack for seeing the good in people and would probably be willing to give Obito a chance to redeem himself. Also, Sakura, with her skills as a medic - ninja, could be an ally. She might help heal Obito if he was injured during the war and see the potential in him to be a force for good.
The 'naruto jinchuriki of the world eater fanfiction' might center around the Jinchuriki's journey. Maybe they have to face challenges that come with being associated with a 'world eater'. This could involve battles against other powerful forces in the Naruto universe who either fear or want to use the power of the 'world eater' within the Jinchuriki. It could also delve into the Jinchuriki's relationships with other characters, like how Naruto's friends might react to this new and dangerous situation.
The fanfiction could explore how Obito's identity revelation affects his relationship with the Akatsuki. Some members may feel used or deceived, while others might see it as an opportunity. It could also show how Obito's true self starts to form new bonds or break old ones within the organization, depending on how his true intentions are perceived.
One possible motive could be to use Sakura as a bargaining chip. If he has some sort of plan against Naruto or the Hidden Leaf Village, Sakura, being a close comrade of Naruto, could be very useful. He might think that by restraining her, he can force Naruto to come to a certain location or make concessions.
Well, not having read the 'naruto jinchuriki of the world eater fanfiction', it's all speculation. The Jinchuriki is bound to be a main character. If it's set in the Naruto universe, Kakashi could also be in it. He might be in a position of trying to protect the Jinchuriki from those who would misuse the 'world eater' power. There could be a group of rogue ninjas who are after the Jinchuriki's power, and they could be major antagonists. And there may be a mysterious character who has a connection to the origin of the 'world eater' and has their own agenda regarding the Jinchuriki.
Well, it could be about Naruto somehow obtaining the power of Son Goku. Maybe there's a strange jutsu that fuses their powers. Naruto could use Son Goku's strength in battles, like having his speed and ki blasts along with his own ninja skills.
Yugito Nii is a very popular character as she is the actual 2 - Tails Jinchuriki in the Naruto series. In fanfiction, she often takes center stage, whether it's in stories about her training or her battles against powerful foes.
One popular sakura and obito fanfiction is 'The Unseen Bond'. It delves into a world where Sakura discovers Obito's hidden past and tries to help him find redemption. Another great one could be 'Sakura's Encounter with Obito', which focuses on their chance meetings and how it gradually changes their relationship. And there's also 'A New Path for Sakura and Obito' that shows them working together to face challenges in the ninja world.
The sad story of Obito and Rin is a key part of the Naruto narrative. Obito was a young ninja with big dreams and a huge crush on Rin. When Rin was seemingly killed in front of him, it shattered his world. He thought that the ninja world was full of pain and betrayal. This led him to be influenced by Madara. He became one of the main antagonists, all because of his love for Rin and the unbearable pain of losing her. His journey from a hopeful young ninja to a vengeful villain is a tragic consequence of Rin's death.