There's 'The Trio's New Dynamic' which delves into how Harry's relationship with Fred and George changes the whole Gryffindor dynamic. In this fanfiction, they might be involved in some pranks that lead to more serious adventures and self - discovery. For example, a prank gone wrong could lead them to discover a hidden part of Hogwarts and in the process, their relationships grow stronger.
There are quite a few fanfictions out there. 'The Trio's Tale' is a great one where it really explores the characters of George, Harry, and Fred in a way that makes their relationship interesting. It often has them facing challenges together and growing closer as a result. And then there's 'Fred's Perspective' which gives a different view on their interactions, especially how Fred sees his relationship with George and Harry.
A third one could be 'Beyond Friendship: Harry and Fred'. In this story, the author might take their relationship to a new level, perhaps starting from a small moment of shared understanding and growing into a relationship that defies the normal boundaries of friendship, all while still being set in the magical world of Harry Potter.
Another theme is loyalty. In these fanfictions, they are often depicted as being extremely loyal to each other, even in the face of difficult situations. This loyalty is what holds their relationship together and helps them overcome various obstacles. They would stand by each other no matter what, whether it's dealing with school bullies or more serious threats from the wizarding world.
Often, there might be a situation where Harry is oblivious to the feelings of Fred and George at first. So, the plot could revolve around how they try to make their feelings known to Harry without scaring him away. This could involve a lot of internal struggle for Fred and George, as they are also brothers and don't want to let their relationship with each other suffer because of their feelings for Harry. There could also be a sub - plot where other characters notice the tension between Fred, George and Harry and either try to help or make things more complicated.
I'm not sure about specific 'Fred George Jealous Harry' slash fanfiction. You could try searching on fanfiction websites like Archive of Our Own. They have a vast collection of fanfictions, and by using the relevant tags and keywords, you might be able to find what you're looking for.
A really good one is 'Among the Marauders' Descendants'. It not only involves the relationship between Harry, Fred and George but also ties in elements of the Marauders' era. It creates a rich backstory and a vivid present - day narrative where the slash relationship between the three characters is developed in a very engaging and believable way.
There's this fanfiction titled 'The Bond of Harry, Fred, and George'. It's popular because it delves into the deeper emotional connection between them. It shows how they support each other through tough times, like when Harry is haunted by Voldemort's presence. Fred and George use their humor and creativity to lift Harry's spirits and help him face his fears.
There's also 'Fred, George and Harry: The Unlikely Trio'. This fanfic delves into how their different personalities - Harry's heroism, Fred and George's cheeky and inventive natures - come together to face various challenges in the wizarding world. It's a story full of adventure and friendship.
You should also consider the relationships they already have in the original story. Harry is friends with Fred and George, but you want to build on that. Maybe have them share secrets or have an adventure that only the three of them can go on. It could be something like finding a hidden magical object in the Forbidden Forest. This would force them to rely on each other and deepen their bond. And don't forget to use vivid descriptions to bring the story to life.
One popular trope is the 'shared destiny' trope. They are fated to be together in some grand plan to save the wizarding world, and this destiny binds them as soulmates.