An OC could be a wizard - in - training from a far - off land who has heard of Gandalf and wants to learn from him. They tag along with the dwarves and Bilbo, bringing their own brand of magic which is different from Gandalf's. Maybe their magic is more nature - based and they can control plants to create barriers or bridges when needed.
Perhaps the dragon OC has the ability to transform into a human - like form. It infiltrates the company of dwarves and hobbits, initially with some ulterior motive. But as the journey progresses, it starts to care for them and uses its dragon powers secretly to aid them against various perils, creating a lot of mystery and suspense in the fanfiction.
A hobbit OC fanfic could focus on a young hobbit who dreams of leaving the Shire to become a great warrior. They set out on a journey against the wishes of their family and face many challenges. Along the way, they meet different races like elves and dwarves and learn from them, all while trying to prove themselves in a world that doesn't expect much from hobbits in terms of combat.
One plot idea could be that the singer OC is a long - lost relative of a hobbit and has a special song that can unlock a hidden treasure in the Lonely Mountain. Another is that the singer OC's voice has the power to tame wild beasts in Middle - earth, and they join the dwarves' journey to protect them from such threats. Or perhaps the singer OC is on a mission to find a rare instrument in the lands of The Hobbit and teams up with the main characters to achieve this.
One idea could be a Hobbit finding their way into Skyrim. Maybe they get mistaken for a child at first due to their small stature. They could bring their Hobbit - like skills of stealth and a love for food. For example, they might start a small cooking business in one of Skyrim's towns, using unique Hobbit recipes and ingredients they manage to find in Skyrim. This could attract all kinds of characters, from the local Nords to the wandering adventurers.
One plot idea could be that the male demon OC is sent to disrupt the quest of the hobbits. He tries to steal the One Ring for his own dark purposes. Another idea is that he forms an unlikely alliance with the hobbits. Maybe he realizes that by helping them, he can gain something in return, like a way to redeem himself. Or perhaps he is in search of a lost relic in Middle - earth and his path crosses with the hobbits, and they end up having to cooperate to find it.
One idea could be that the Hogwarts students go on an exchange program to Middle - earth. They could learn magic from the wizards there like Gandalf and in return teach them some of their own spells. Another could be that the One Ring somehow finds its way to Hogwarts and causes chaos among the students and teachers as they try to resist its power. Or perhaps a character like Harry Potter is transported to Middle - earth and has to use his skills to help the Fellowship in their quest.
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'.
One idea could be that the reader is a healer who is brought to Thranduil's realm to tend to the wounded after a battle. Thranduil is initially skeptical of the reader's abilities but gradually comes to respect and then fall in love with them as they prove their skills.
A good plot could involve the male elf OC being sent on a mission by his elven king to spy on the dwarves' journey. But during this, he realizes that the dwarves are not as bad as he thought and decides to help them instead. He could also be cursed by an evil sorcerer, and the only way to break the curse is to complete a series of impossible tasks. This could lead him to team up with unlikely allies, like a hobbit or a wizard. Additionally, his family's past could come back to haunt him, and he has to face his ancestral demons to save his people.
Bilbo could get hurt in a cave - in by a hidden trap. His companions would then need to figure out how to treat his wounds and get him out of the cave safely. This would create a lot of tension as they might not have all the necessary supplies with them.