Is your character well-written
Many authors and fanfiction writers fall into the whole of bad characters. these include Mary Sues, grumpy goth characters, evil villains, characters being nothing but an archetype, or characters being nothing but an offending steryotype.
If your worried that you might be one of those writers, find out now! It's better than figure out early and write better characters than learn to late and be hated as an author.