Yes, there might be. There are many creative fanfiction writers in the world who like to combine different fictional universes. Some might have come up with the idea of integrating Harry Potter and Obito Uchiha. You can try searching on popular fanfiction websites like Fanfiction.net or Archive of Our Own to see if there are any such stories.
A possible plot could be that in a parallel dimension, Harry Potter is actually Obito Uchiha reincarnated. He is born into the wizarding world but still has some latent memories and powers from his past life as Obito. As he grows up in Hogwarts, he discovers his unique abilities which are a blend of magic and the powers of the Sharingan. He uses these to uncover a hidden conspiracy within the wizarding world that is related to an ancient dark magic that has similarities to the dark powers in Obito's original world. Along the way, he has to deal with his own inner demons, just like Obito did, and also face off against the traditional threats in the Harry Potter universe like Voldemort and his followers, but with a whole new set of skills and a different perspective due to his dual - natured identity.
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.
Sakura could be an unexpected character to have the Sharingan. It would completely change her character dynamics. She could use it to enhance her medical ninjutsu, seeing the internal body structure more clearly. Also, she could become a more formidable fighter, using Sharingan - based genjutsu to her advantage.
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.
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.
Well, in fanfiction, one way could be that some Kumo ninjas are given the Sharingan as a gift or a curse from an ancient being. They then start to form a special group within the village dedicated to understanding and mastering the Sharingan. This group would share their knowledge with others, and over time, the Sharingan becomes an important part of Kumo's ninja heritage, with its own set of training methods and traditions.
A great Naruto Obito fanfiction could explore his relationship with Rin in more depth. Maybe it's a story where Obito has a chance to save Rin from dying, and how that would change his path. It could also show how his relationship with Naruto might be different as a result.