You can start by looking on fanfiction.net. It has a vast collection of fan - made stories across various fandoms. There are also some great ones on Archive of Our Own (AO3). Many Tumblr blogs are dedicated to sharing and recommending fan fiction love stories too.
A great fan fiction love story often stays true to the original characters' personalities. If it's a story about characters from a well - known series, and the writer manages to capture their essence while adding a new romantic plot, it can be really good.
Another option could be DeviantArt. While it's mainly an art - sharing platform, there are also written works, including fan fictions. You might be able to find some unique love fan fictions there. But it may require a bit more searching as it's not as specialized in fan fiction as AO3 or FanFiction.net.
There's this fanfic called 'Alliance of the Martian'. It's about Martian Manhunter forming an unexpected alliance with some of the villains in the DC universe. It's a unique take as it shows how he tries to understand their motives and turn them into allies. It's full of twists and turns that keep you hooked from start to finish.
Well, there's a fan fiction called 'Xenomorphs Among Us'. It's really cool because it imagines a world where xenomorphs have infiltrated human society in secret. Then there's 'The Xenomorph Queen's Reign' that delves into what would happen if the queen had more intelligent and far - reaching plans. Also, 'Xenomorph Encounters in Space' is exciting as it's set in the vastness of space and the battles that ensue there.
One great 'Iron Fist' fan fiction could be about Danny Rand exploring a new dimension in the martial arts world. Maybe he discovers a hidden temple where a unique fighting style exists that he has to master to defeat a new, powerful enemy.
One of the best Harry Potter fan fiction stories is 'The Draco Trilogy'. It delves deep into the complex character of Draco Malfoy, showing his growth and redemption in a way that the original series only hinted at. It gives a new perspective on his relationship with Harry and other Hogwarts students.
One of the best is 'Pride and Prejudice' by Jane Austen. The relationship between Elizabeth Bennet and Mr. Darcy is a classic. They start with misunderstandings and prejudices against each other. Elizabeth thinks Darcy is too proud, and Darcy has some false impressions of Elizabeth's family. But as the story unfolds, they gradually see the real person behind the facade and fall in love. It's a story that beautifully portrays how love can overcome initial differences and social barriers.
In my opinion, the best fan fiction is one that stays true to the essence of the original work while still being creative. It should respect the lore and the world - building of the source material. For instance, a Star Wars fan fiction should follow the rules of the Force and the different species and cultures in the galaxy far, far away. Also, fan interaction can play a part. If a fan fic has a community of readers who are excited about it, discuss it, and even contribute ideas, it can enhance its status as a great piece of fan - created work.
Well, I really like the fan fiction 'Time's Echo'. It's about a character who accidentally discovers a time - traveling device and has to deal with the chaos that ensues. It has a great plot that keeps you on the edge of your seat. Then there's 'Lost in Time Lanes', where the main character travels back in time to meet their ancestors. The descriptions of the different time periods are really vivid. Also, 'Time Traveler's Dilemma' is interesting. It shows how small changes in the past can have huge impacts on the future.