A guide to writing HP fan fiction

Character development

First, I will leave you with two definitions:

Flat characters: Flat characters are two-dimensional in that they are relatively uncomplicated and do not change throughout the course of a work.

Round characters: round characters are complex and undergo development, sometimes sufficiently to surprise the reader.

If we consider Crabbe and Goyle from the series, we can see that they are flat characters because they go through no change in the entirety of the discourse. They serve their purpose, and that is why they're fine as flat characters. However, your main character in the story shouldn't be a flat character because then readers will lose interest in them. Here is a list of things I have found that make your main character flat.

Making their whole story revolve around finding love.
Love is such a wonderful additive to the plot line, and gives your main character a way in which they can showcase their emotions. However, if the sole reason they're in the story is to find love, they lack any real purpose other than that.

Not letting your MC go through any types of obstacles/challenges
If you're afraid of putting your main character through some hard times, they aren't going to be able to learn some life lessons that they can use later on in their story. Challenges are necessary for them to grow as a person, they're just like any other human being.

Making them perfect in every way
Your readers will yearn to relate to the main character of your story. If you make them I flawed and brilliant at everything, the chances are they'll lack interest. It also won't be any fun for you writing a character that is perfect, when this world is anything but.

Making them act like a background character
If all they do is study, eat, watch quidditch and go to lessons, there is no sense of adventure in their story or world. This is where creating a strong plot line is important, because these things should just be apart of the story, not the main focus.