Some popular tropes include the 'unexpected friendship' trope. Characters from Naruto and Fire Emblem who you wouldn't expect to get along become close friends in the harem fanfic. The 'training together' trope is also quite common. They train to improve their skills and in the process, their relationships deepen. And the 'mystery element' trope, where there's a mystery in the harem setting, like a hidden power or a secret about one of the characters that the others have to figure out.
Well, a typical trope is the 'rivalry - turns - to - love' one. In these fanfictions, two characters who initially compete for the protagonist's attention end up falling for each other. Also, the 'protector' trope is seen often. A character from either Naruto or Fire Emblem will take on the role of protecting the others in the harem, which helps to strengthen their bonds. There's also the 'culture clash' trope as the two different universes have their own unique cultures that create interesting situations when combined in the fanfic.
One popular trope is the 'fish out of water' situation. For example, a Naruto character might find themselves in the Fire Emblem world and have to adapt to its different combat styles and social hierarchies. Another is the power - up trope, where characters gain new abilities or powers through their interactions in the harem setting. And of course, the relationship - building trope is common, with characters slowly developing feelings for each other over time through shared adventures and challenges.
One popular trope is the 'fish out of water' story. For example, a character from Fire Emblem Fates suddenly finds themselves in the Naruto world and has to adapt to the new environment, culture, and combat system. Another is the power - up trope. A Naruto character might gain new abilities inspired by Fire Emblem Fates, like the ability to use a Fire Emblem weapon.
One popular trope is the 'protector and protected' dynamic. Given Robin's strategic mind and combat skills, he often ends up protecting Lissa, which can lead to a sense of closeness and the development of deeper feelings. Another trope is the 'opposites attract' where their different personalities draw them together. Lissa's cheerfulness can brighten Robin's more serious demeanor.
Another common trope is the transformation. A character in the Fire Emblem universe might get turned into a vampire, either by accident or as part of a dark plot. This then leads to their internal struggle with their new identity, as they have to balance their old loyalties and values with their new vampiric instincts.
First, you need to decide on the main character. Will it be a Naruto character in the Fire Emblem world or vice versa? Then, think about the personalities of the characters you want in the harem. After that, create a basic plot. It could be about saving a world, or finding a powerful artifact. And don't forget to do some research on both Naruto and Fire Emblem universes to make the story more accurate.
One popular trope is the 'powerful Naruto' where he is even more powerful than in the original series. This attracts multiple female characters to him. Another is the 'outsider acceptance' trope, where Naruto, who was once an outcast in the village, now has a harem of girls who fully accept and love him for who he is. And there's also the 'adventure harem' trope where Naruto goes on various adventures with his harem members.
A third popular trope is the 'forbidden love' aspect. Maybe a relationship between a Naruto character and a Bakugan - related character is frowned upon in their respective worlds. This adds an element of drama and tension to the fanfiction. For example, if a shinobi from Naruto falls in love with a Bakugan trainer, their different cultures and duties might create obstacles for their relationship.
Some tropes in this type of fanfiction include the 'damsel in distress' but with a twist. Maybe a Until Dawn character is in trouble and the Naruto character uses their unique skills to save them. There's also the 'rival turned lover' trope. Two characters who were initially competing for the main character's attention end up falling for each other instead. And the 'training montage' trope can be adapted. Instead of just Naruto - style training, it could be training to survive in the Until Dawn horror - filled environment.
One popular trope is the 'fish out of water' scenario. For example, a character from Naruto suddenly finding themselves in the world of Fullmetal Alchemist and having to adapt to its rules and customs while also dealing with a harem of characters from both universes. Another is the power - up trope. A character might gain new abilities by combining the alchemy knowledge from Fullmetal Alchemist with the ninja skills from Naruto, all while being in a harem - type situation where different characters are attracted to their new - found power and unique personality. Also, the 'rivalry for love' within the harem is quite common, with characters from Naruto and Fullmetal Alchemist vying for the main character's affection.
One way could be Naruto's ninjutsu skills being translated into unique combat arts. For example, his Shadow Clone Jutsu could be a special ability that creates temporary clones to distract enemies in battle, similar to how some Fire Emblem characters have skills to create decoys.
One challenge is combining the two very different worlds. Naruto has ninjas with chakra and unique jutsu, while Fire Emblem has its own system of magic, classes, and medieval - like settings. It's hard to make them blend seamlessly.