It depends on the specific situation and the character's personality. Some heroes might have moments of fear but overcome them through their determination and sense of duty.
It could be about a character in the My Hero Academia universe who defies the traditional concept of a hero. Maybe they don't have the typical flashy quirk but still manage to be heroic in their own way, like using intelligence or empathy.
In a My Hero Academia fanfiction, Gohan could be seen as a hero from another dimension. His moral code, which is similar to the heroes in MHA, would make him a natural fit. He could also train the students in new ways of combat, using his martial arts skills combined with his Saiyan abilities.
Sasuke's powers could potentially be adapted in interesting ways in the MHA universe. His Sharingan could be seen as a unique quirk. For example, it could give him enhanced perception abilities similar to some quirks that allow for better combat prediction. He might be able to analyze an opponent's moves and fighting style just like in the Naruto world, but it would be framed within the context of MHA's hero - villain battles.
Goku's powers would be a game - changer in the MHA universe. His ability to fly would be unique among the heroes there. His Saiyan rage mode could be like an extreme version of a quirk awakening. But he might also have trouble fitting in at first. He's used to a more straightforward fight - or - be - fought world, while MHA has a lot of rules and regulations for heroes. However, his pure heart and desire to protect would surely make him a beloved hero.
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.
Killua has a very stealthy side to him as well. In a My Hero Academia fanfiction, this could be manifested as a quirk that allows him to become invisible or at least very difficult to detect. He could use this in combination with his speed to surprise enemies. It would also be interesting to see how he would interact with other characters like Deku and Bakugo, perhaps teaching them some of his combat techniques.