There are many good ones. For My Hero Academia, 'The Quirkless Hero' is a fanfic that flips the script by having a quirkless character rise to hero status in a unique way. In Mob Psycho 100 fanfiction, 'Mob's New Adventure' is fun. It takes Mob on a journey outside of his normal environment. Also, for My Hero Academia, 'The Underground Hero' is a great fanfic that shines a spotlight on the often - overlooked underground heroes.
Training scenarios are often explored in fanfiction. How would the characters train in a combined setting? There are also fanfics that deal with the idea of redemption for villains. In the context of these two series, it could be interesting to see how a villain from one might be redeemed in the other's world. Additionally, the exploration of different cultures within the two series can be a theme, as both have unique settings and character backgrounds.
A crossover might also involve Reigen from Mob Psycho 100 trying to start a business in the My Hero Academia world. He could claim to be a quirk - enhancer trainer or something similar. It would be hilarious to see him interact with heroes like All Might or Endeavor, trying to convince them that his 'methods' are legitimate while they're just confused by his over - the - top personality.
I really liked 'A Different Kind of Hero'. In this fanfic, it delves deep into how the concepts of power and heroism from both series interact. The author does a great job of bringing together the characters from both shows. For example, Shigeo Kageyama's calm and collected nature contrasts well with some of the more brash characters in My Hero Academia, creating some really engaging character dynamics.
In My Hero Academia fanfiction, a common theme is character development, like how Midoriya grows in power and as a person. Another is exploring different quirk combinations. For Mob Psycho 100, themes often revolve around Mob's struggle with his psychic powers and his relationships. Friendship is also a big theme in both, showing how characters support each other through tough times.
You can try fanfiction platforms like Archive of Our Own (AO3). There are tons of fanfics there for both Mob Psycho 100 and My Hero Academia. Just use the search function and type in the relevant tags for each series. You might also check out FanFiction.net, but AO3 usually has a wider variety and more updated content.
One idea could be a crossover where Mob and Midoriya meet. Mob's psychic powers and Midoriya's One For All could lead to some really interesting team - up scenarios. Maybe they have to face a villain who can manipulate emotions and they combine their powers to defeat the villain.
I really like the idea of Shigeo 'Mob' Kageyama and Izuku Midoriya interacting. Izuku is so determined to be a hero despite being initially quirkless, and Mob has such strong psychic powers but is often so reserved. They could learn a lot from each other. Izuku could teach Mob about the importance of having a clear goal in using his powers for good, while Mob could show Izuku some of the more spiritual and internal aspects of power control.
The character interactions are a big draw. Characters from both shows have such distinct personalities. You could have Deku from My Hero Academia meeting Mob and learning about his way of handling his power. Their different outlooks on heroism and self - worth would make for some really interesting conversations and character development.
A great crossover often involves a good balance of the powers from both series. For example, when Reigen from Mob Psycho 100 somehow gets involved in a My Hero Academia battle. His con - artist skills could be used in a really unexpected way, like tricking the villains into believing he has a powerful quirk.
In a fanfiction crossover, it could be that the villains from both universes team up. The Claw organization from Mob Psycho 100 and the League of Villains from My Hero Academia might form an alliance. This would force the heroes from both series, like Shigeo Kageyama and Izuku Midoriya, to work together. They'd have to learn from each other's strengths and weaknesses in order to defeat this powerful new threat.