In the fanfic, it might be that the people around Harry treat him as an ordinary person most of the time. So, he doesn't get the sense that he is a hero. For example, his friends might joke around with him and not give him the 'hero - treatment', which makes him oblivious to his heroic status.
A possible plot twist could be that the heirship is not what it seems. Maybe it's not related to a noble wizarding family but to an ancient, forgotten magic. Another twist could be that someone else has been manipulating events to make Harry think he's the heir when he's not, or vice versa.
It could be that he is constantly compared to other more 'flashy' characters in the fanfic world. Those characters might have more obvious powers or more dramatic backstories. So, Harry, with his more understated heroism, doesn't think he measures up and doesn't realise he is a hero too. He feels like he's just an ordinary person in the midst of these seemingly more extraordinary individuals.
The author might use various methods. For example, they could keep key information from Harry's past hidden from him. Maybe they show his normal wizarding life at Hogwarts, with no signs of his heir status, so that when small hints start to appear, it creates mystery. His friends might not notice anything different either, which adds to the enigma.
Well, to draw a comic game well, you should master the basics of drawing, like anatomy and perspective. Also, study the styles of popular comic games for inspiration. Don't forget to plan your layout and composition.
One popular example is 'Snow White' where the main character has beautiful white hair. Another could be characters from Japanese anime like 'Elsa' from 'Frozen'.
Sonic comic faces often have big, expressive eyes and a wide range of emotions depicted. They might have distinct color schemes and unique designs for each character.