There's 'A New Hope for UA' which is also a very good MHA OC fanfiction. In this, the OC has a quirk that is initially seen as weak but they manage to use it in innovative ways. The fanfiction does a great job of integrating the OC into the existing MHA universe, with lots of references to the original series.
Saitama's overpowered strength would likely be a huge disruptor in the MHA world. His simple yet extreme power of being able to defeat any enemy with one punch would make him a top - tier hero instantly. Genos, with his advanced cybernetic enhancements, would also be quite formidable. He could potentially be part of the development of new support items or hero gear in the MHA universe, given his knowledge of technology. And his combat abilities would put him in the ranks of the stronger heroes there.
Saitama's overpowered nature would completely disrupt the power balance in the MHA universe. His simple yet extreme strength and speed would make him an outlier. For example, in MHA, most heroes have to strategize and work in teams against villains. But Saitama could just one - punch most threats away. This would change the way villains operate as well, perhaps making them more desperate or more likely to target Saitama directly. It could also lead to interesting scenarios where heroes might be both in awe and a bit intimidated by his presence.
Well, you could have an MHA OC who is a villain - turned - hero. Their backstory could involve being mistreated and turning to villainy, but then being inspired by the heroes to change their ways. Maybe they have a quirk that involves shadow manipulation, which they used for evil before but now use for good. Or an OC that is a tech - genius and creates their own high - tech hero gear, much like Mei Hatsume but with their own unique style. Also, an OC with a healing quirk could be interesting, especially if they have to deal with the moral dilemma of whether to heal villains or not.
One common theme is self - discovery. The reincarnated OC often has to figure out who they are in this new world and how their previous life and new circumstances interact. Another is the struggle for power. Since the MHA world is centered around quirks, the OC usually has to find a way to gain power or use their unique skills.
First, you need to create a unique villain OC. Think about their backstory, what made them turn bad. For example, if they had a tragic childhood event like being bullied or abandoned. Then, consider their powers. It should be something that fits the MHA universe. Maybe a power related to shadows or mind control. Also, give them a distinct personality. Are they cold - hearted, or do they have a soft side? When writing the fanfiction, start with an interesting hook to draw readers in, like a mysterious crime scene caused by your villain OC.
One interesting Saitama OC fanfiction could be about an OC who is a new hero in the City-Z. This OC might have a unique power that complements Saitama's strength in unexpected ways. For example, the OC could have the power of telepathy and helps Saitama communicate with monsters before fighting them, adding a new dimension to the battles.
Saitama would probably have an interesting dynamic with Bakugo. Bakugo is brash and confident in his abilities, but Saitama's nonchalant power would likely humble him. Genos could form a partnership with Uraraka. Uraraka's zero - gravity quirk could be useful in combination with Genos' combat skills. They could work together on rescue missions. And Saitama could also have a mentor - like relationship with some of the UA teachers, sharing his unique view on heroism that doesn't rely on quirks but on personal effort.
A lot of MHA female OC fanfiction involves the OC being part of a team. For instance, she could be in a team with some of the less - prominent characters from the original series and they go on to do heroic deeds. Some stories focus on the female OC's journey to master her quirk, perhaps with the help of an older, more experienced hero. There are also those that explore the OC's family background and how it ties into her life as a hero - in - training, like if her family has a history of quirks that were once feared or misunderstood.
Check out YouTube channels or podcasts that focus on MHA fanfiction. They sometimes do reviews or showcases of great MHA OC fanfictions. Additionally, following MHA fan artists on platforms like Twitter can also lead you to discover great fanfictions. Often, fan artists are also into fanfiction and can point you in the right direction.