Robin could be a thief - like character. He could steal important items from the enemy, just like Bilbo stole the One Ring from Gollum. His small size and agility would make him good at sneaking around, and he could provide valuable information to the Fellowship by eavesdropping on the enemy's conversations.
Robin could be a bard in the crossover fanfiction. Bards play an important role in Middle - earth, like Aragorn who is also a great storyteller. Robin could use his songs and stories to boost the morale of the people. He could sing of the great deeds of the heroes, inspiring them to greater feats. His music might also have some magical properties, like calming the beasts or revealing hidden paths.
One way could be that Robin is a lost traveler from another realm who stumbles into Middle - earth. Maybe he has unique skills like archery that could be useful in the battles against Sauron. He could also form an alliance with the Fellowship, sharing his different perspective and knowledge from his own world.
Perhaps Harry is a diplomat in the fanfiction. He uses his charm and wisdom to negotiate between different factions in Middle - earth, like the elves and the dwarves. He might be crucial in maintaining peace. Since he is an Elf Lord, he could also lead the elves in battles or in the protection of their lands.
He could be a protector. Just like the elves in Lord of the Rings are often guardians of their realms, Harry could use his elf - like abilities to safeguard a particular place or group of people in the fanfiction.
She might be a warrior. Sakura has shown great strength and combat ability in Naruto. In the Lord of the Rings fanfiction, she could be a fierce fighter against the forces of Sauron. She could use her physical strength and perhaps learn some new combat techniques in Middle - earth to battle orcs, trolls, and other evil creatures.
One way it could work is by having Naruto characters in Middle - earth. For example, Naruto with his shadow clone jutsu could be a great asset in the battles against Sauron's forces. He could create clones to confuse the orcs and trolls. Meanwhile, characters from 'Lord of the Rings' could learn from Naruto's ninja skills. Frodo might pick up some stealth techniques from Naruto's training.
One possible plot could be that Eragon somehow gets transported to Middle - earth. He could meet Aragorn and learn from his leadership skills. Maybe they would join forces to fight a common enemy like a new breed of dark creatures created by a combination of Sauron's magic and the dark forces from Eragon's world.
In such a crossover fanfiction, Boromir could be a diplomat from Middle - earth sent to Westeros. He would be shocked by the political intrigue and the lack of honor in some of the power - hungry characters. He might try to introduce the concept of the Fellowship and unity to the warring kingdoms of Westeros.
In Lord of the Rings fanfiction, Sakura could potentially be a powerful mage. She might use her skills to assist the Fellowship in their battles against the forces of Sauron. For example, she could create barriers to protect them from enemy attacks.
A really interesting plot could be that Naruto is mistaken for a powerful wizard. He gets involved in the battle against Sauron. His Rasengan could be a powerful weapon against the orcs and other dark creatures. Also, his friendship with the characters in Middle - earth would grow as they see his loyalty and determination, much like how his friends in the Naruto world value him.
One possible plot could be Sasuke finding himself in Middle - earth. He might be mistaken for an elf at first due to his appearance. He could then get involved in the fight against Sauron. Maybe he uses his Sharingan to detect the presence of orcs or other dark forces. His ninja skills would be quite useful in battles, like his speed and ability to move stealthily.