A prevalent theme is the exploration of different worlds. The human reader enters the elven realm and has to adapt to its beauty and mystery. There's also the theme of sacrifice. Sometimes the human might sacrifice their own world or future for Thranduil, or vice versa. And of course, there's always the theme of love's power to bridge the gap between two very different beings.
One great 'Thranduil x Reader' fanfiction is 'The King's Heart'. It beautifully portrays the relationship between Thranduil and the reader. The author does an amazing job of creating a vivid world and a slow - burning romance. Another good one is 'In the Elven Realm'. It shows how the reader becomes an important part of Thranduil's life in the elven kingdom. There are also some really nice fanfics on Archive of Our Own that are worth exploring if you like this pairing.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). There are numerous works there. Just use the search function and type in 'Thranduil x Human Reader' and you'll get a whole list of stories. You can also check out Fanfiction.net, though the selection might be a bit different.
One common theme is the power of love across different species. Since Thranduil is an elf and the reader is presumably a human or from another race, their relationship often explores how love can bridge those gaps. Another theme is adventure. The reader may get involved in Thranduil's world of elves, which is filled with magic and danger, and they go on quests together.
One common theme is the allure of the elven world. Fanfictions often explore the beauty and mystery of Thranduil's realm, with the reader being drawn into it. Another theme is the power dynamic. Thranduil is a king, so there's often a play between his authority and the reader's more ordinary or unique position. Love against odds is also a big theme. Since they come from different worlds or statuses, their relationship has to overcome various obstacles.
A prevalent theme is the discovery of new emotions. Thranduil, being an ancient and somewhat aloof elf - king, discovers new depths of love and passion through his relationship with the reader. The fanfictions also often have the theme of protection. Thranduil wants to protect the reader from the dangers of his world, and the reader may also have a desire to protect Thranduil's heart and his kingdom in some way.
In another long story, the reader could be a healer who is brought to Thranduil's court to tend to the wounded. Thranduil initially dismisses the reader as just another mortal. However, the reader's skills and kind heart start to win over the king. The story could then unfold with the reader having to deal with the politics of the elven court while also falling in love with Thranduil. There would be many obstacles like jealous courtiers and old elven traditions that they have to overcome.
One common theme is the clash of cultures. Since Thranduil is an elf and the other character is human, their different ways of life, values, and beliefs often collide. For example, elves might value nature in a more spiritual way compared to humans.
One great 'thranduil x reader romance fanfiction' is 'A Love in the Woodland Realm'. It beautifully portrays the relationship between Thranduil and the reader. The author does an amazing job of creating a vivid setting in the elven kingdom. The chemistry between the characters is palpable and the story is filled with sweet moments.
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.