For My Hero Academia, the theme of hero - villain dynamics is really popular. Fanfics often explore what makes a villain and if they can be redeemed. In Mob Psycho 100, the idea of self - discovery is huge. Mob trying to figure out who he is beyond his powers is a common theme. Also, in both, the theme of family, whether it's the found family in My Hero Academia or Mob's real family, is often explored.
In My Hero Academia fanfiction, the theme of power corruption can be seen a lot. How too much power can change a hero into something else. For Mob Psycho 100, the theme of acceptance, both self - acceptance and acceptance from others, is quite popular. And in both, the theme of school life and how it shapes the characters is a significant part of many fanfictions.
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.