I think Legolas could be really interesting. In 'The Hobbit', there are no elves from Mirkwood really involved in the story in the way Legolas is in 'The Lord of the Rings'. So, if you cross over the two, you could explore how Legolas might interact with the dwarves in a different context, considering the historical tension between elves and dwarves. He could also use his skills as an archer in new and unexpected ways, perhaps influenced by the events in 'The Hobbit' that he hears about from Gandalf or other characters.
I think it would be really interesting to focus on Hermione. She's so intelligent and curious. In Middle - earth, she could study the different magic and lore there. She might be the one to figure out how to combine the magic of the two worlds. For example, she could try to find a way to use the magic of Middle - earth to defeat Voldemort or help the Fellowship in a different way.
Naruto himself would be really interesting. His boisterous personality and never - give - up attitude would be a contrast to the more solemn characters in 'Lord of the Rings'. He could bring a new energy to the story, and his unique jutsu would make him a force to be reckoned with in Middle - earth.
I think Frodo and Lucy would make an interesting pairing. Frodo is burdened with the One Ring and has seen a lot of darkness, while Lucy is full of innocence and hope. Their interactions could show how the two different worlds' outlooks can influence each other. For example, Lucy's unwavering faith might give Frodo some new strength in his fight against the Ring's power.
Another great crossover could be between Gandalf and Urahara. Gandalf is a wise and powerful wizard, and Urahara is a very intelligent and somewhat mysterious character in Bleach. They could share their knowledge of magic and strategy. Gandalf might be intrigued by Urahara's unique inventions and scientific approach to spiritual matters, while Urahara could learn from Gandalf's vast experience and wisdom in dealing with different races and powers.
Saphira, Eragon's dragon, and Gwaihir, the great eagle in Lord of the Rings. These two powerful flying creatures could form an alliance. They could communicate in their own ways and work together to provide aerial support during battles, as well as help in transporting important characters across great distances in Middle - earth and Eragon's world.
One idea could be that Bilbo Baggins discovers a hidden relic during his adventures in 'The Hobbit' that later becomes crucial in the fight against Sauron in 'The Lord of the Rings'.
Raphael could be really interesting. In the 2003 version, he is hot - tempered and tough. In the 2012 version, he also has a strong personality. Seeing how he reacts to his counterpart and how they might either clash or bond could be a great focus. Maybe they have a friendly rivalry as they compare their fighting skills.
Ross could be really interesting. Since he's an archaeologist, in a crossover with a show like 'Indiana Jones' (in a fanfiction sense), he could go on an adventure with Indiana Jones. Ross would bring his academic knowledge while Indy would have the practical experience. Their interactions would be filled with Ross trying to over - analyze everything and Indy just wanting to get the job done.
Chiaki Nanami could be an excellent choice. She is the Ultimate Gamer, so if you cross her with a digital or virtual world, there are so many possibilities. She could use her gaming skills to navigate through a new digital realm, like a Matrix - like world. Her calm and intelligent nature would also make her a great character to lead the group in a crossover situation. She could figure out the rules of the new world quickly and help the others adapt.
Definitely Harry Potter and Frodo Baggins. Harry has faced his own share of dark forces in the form of Voldemort, and Frodo has carried the burden of the One Ring. They could bond over their experiences of being thrust into dangerous and world - saving quests. Another interesting pairing would be Hermione Granger and Bilbo Baggins. Hermione's thirst for knowledge and Bilbo's love for stories and adventures could lead to some great exchanges.