It can be hard as a writer to take a step back from our stories and separate what’s on the page and what’s in our heads. After all, we know the characters like they are family members. We know their habits, motivations, and personalities off by heart. It’s obvious to me, for example, that Harry is a born optimist and hopeless romantic who is out-going in public but tends to prefer the company of a few select people, is terrified of being abandoned, and is still struggling to come to terms with the death of his twin sister. But is it obvious to you?
Try this as an exercise: Make a list of your characters traits, habits, motivations. Anything that makes them who they are as a person.Then go through your first couple of chapters and make a note of each line that shows these. You won’t get everything about them out early on, and of course characters change as stories progress, but it will help you see if your writing is showing them as you want.
Then get a reader to go through the text and pull out any traits they think the character shows, and the lines that gave them that impression. Hopefully they’ll pick out the same things as you did. You might need to get a couple to go through, as some people might miss things that others pick up on. But if your readers repeatedly aren’t seeing what you’re seeing, or are seeing the character in a different light, then you know you’ve got a problem with how they are being presented.