I don't have enough context to determine exactly who 'garp' is. It could be a newly created character by the fanfic writer, or it might be a character from a relatively unknown story that is being incorporated into the 'ace fanfic'.
I'm not sure which work you're referring to. Please provide more context information such as the title of the work, author, year, region, etc. so that I can better help you answer your questions.
You need to have a good story first. Then, focus on the character designs and make them unique and appealing. Also, pay attention to the frame composition and the use of colors.