One common theme is the exploration of their relationship in an alternate universe. For example, they might be in a situation where they are both heroes or have different backstories that bring them closer together.
A common theme is the exploration of an unexpected relationship. Given their different roles in the My Hero Academia world, it's interesting to see how writers bring them together. Another theme could be the impact their relationship has on Izuku Midoriya.
One common theme is mentorship. All Might is often portrayed as a mentor to the OC, guiding them in their journey to become a hero.
A lot of all might x endeavor fanfictions also touch on the idea of redemption. Endeavor has a rather complex backstory with his family issues, and in some stories, All Might plays a role in his journey towards redemption. They also might explore the theme of mentorship, where either one could potentially mentor the other in different aspects, like All Might teaching Endeavor about public relations as a hero, or Endeavor helping All Might with some combat techniques. There's also the theme of friendship that develops over shared experiences, such as fighting against a common enemy or dealing with the politics within the hero community.
One common theme is the power of mentorship. All Might being Deku's mentor, fanfictions often explore how that relationship affects Deku's growth. Another theme is the transfer of ideals. All Might's 'Plus Ultra' attitude is passed on to Deku in many stories.
One common theme is redemption. Since Endeavor has had a rather dark past in terms of his family relations, many fanfictions explore him finding redemption through his interactions with All Might. Another theme is the exploration of power dynamics. They are two very powerful heroes, and fanfictions often look at how they balance their powers and respect for each other.
One place to find inko x all might fanfic could be Archive of Our Own (AO3). There are often various fan - created stories there. Just search for the relevant tags and you might discover some interesting ones.
Another theme could be admiration. All Might is a symbol of hope and David Shield, being in the hero support field, might look up to him. Fanfictions could explore how Shield's admiration for All Might affects his work and decisions. For instance, he might be inspired to create more advanced support items because of All Might. There could also be themes related to their different roles in the hero world and how they bridge the gap between science and heroics.
One interesting plot idea could be that All Might and Inko meet during a Parent - Teacher event at UA. They start to bond over their shared concerns for their children, Izuku and his development. As they interact more, they discover they have a lot in common, like their strong sense of justice. This could lead to a slow - burn romance where they support each other through the various challenges in the hero world.
You can try fanfiction websites like Archive of Our Own (AO3). There are usually a wide variety of fanfictions there. Just search for 'All Might x Inko' in the search bar and you'll likely find many different stories with different themes and styles.
A frequent theme is the backstory exploration. Writers often create scenarios where we learn more about their pasts and how those pasts might have led to their current relationship. There can also be themes related to hero training. Maybe they team up to train students in some fanfictions, and we see how their teaching styles blend or clash. Also, some fanfictions explore the idea of them facing a common enemy together and how their bond grows stronger through that experience.