In such a fanfiction, from Naruto, Sakura could be in the harem. She's strong - willed and has her own set of skills. From My Hero Academia, Ochaco Uraraka could be there. She's kind - hearted and has an interesting quirk. And of course, Hinata from Naruto is also a likely candidate with her shy yet determined personality.
There's also 'Izuku's Harem Adventure'. In this fanfiction, the author creates unique scenarios where Izuku finds himself in the middle of a harem. It has great character development for not only Izuku but also the members of his harem, exploring their individual personalities and how they interact with Izuku.
Another theme is power - up in relation to relationships. Sometimes, the support from his harem members helps Izuku grow stronger in his hero - related abilities. It shows how his personal life can influence his development as a hero.
Ochaco Uraraka is a common character in the harem. Her kind and friendly nature makes her a likely candidate. Momo Yaoyorozu is also often included. Her intelligence and elegance add an interesting dynamic to the harem. And Tsuyu Asui could be part of it too, with her unique personality.
One theme is the adaptation of the original story's power dynamics. In a genderbend harem fanfiction of Boku no Hero Academia, the powers might be used in different ways depending on the new gender of the characters. Also, friendship and rivalry often play a role. The characters in the harem may be friends who also compete for the affection of the main character, or they could be rivals who gradually develop feelings for each other.
Obviously, Izuku Midoriya is the central character. Then there are often characters like Ochaco Uraraka, who could be part of the harem as she has shown an interest in Izuku in the original series. Tsuyu Asui might also be included as she is a close friend and could potentially develop deeper feelings for Izuku in fanfiction.
One common element is the crossover aspect. Since it's a fanfiction combining Naruto and My Hero Academia, there's usually a way for the Naruto characters to enter the MHA world or vice versa. Another is the harem setup itself. There are multiple female characters, often from both series, who are attracted to the main male character, whether it's Naruto or a character inspired by Naruto. Power - ups are also common. The main character might gain new abilities or combine the powers from both universes in these fanfictions.
First, give your OC a distinct personality. They could be shy and reserved but with a hidden strength, or super confident and a bit of a troublemaker. Next, design a unique quirk. It could be something related to nature, like controlling plants, or a more mental-based quirk like mind - reading. For appearance, think about what would make them stand out in the My Hero Academia world. Maybe they have colorful hair or a really cool costume. Also, consider their backstory. A tragic past can add depth, like if their family was killed by villains and they are determined to become a hero to avenge them.
One idea could be to focus on a new student at UA who has a unique quirk that attracts the attention of multiple characters. For example, a quirk that allows the user to see into people's true emotions. This could lead to some interesting interactions with characters like Deku, Bakugo, and Todoroki. They might all be intrigued by this new student in different ways, and a harem dynamic could develop as they compete for the new student's attention.
Power and how it attracts others is often a theme. In these fanfictions, the main character with unique powers, like Naruto's Nine - Tails chakra or a hero's quirk in Boku no Hero Academia, might draw the attention of multiple characters, leading to a harem situation. Also, the idea of friendship evolving into something more within the harem is quite common.