Personality. Its the one thing that everyone has (well most people) and your character has to have one too! Surprise, surprise. What you thought that your character could just do all the stuff in the book and not have any substance as a person?

Now we all know what kind of people that appeal to a mass audience, the funny comical people, the straight up jerks, the sweet guys and bad girls. But I think that what makes a character special to me is when they have a very unique character trait. Like if the character loves sausages, or lives off tacos. Little things that which can be slipped in through out.

A character's personality can have flaws as well (they are human after all). Have them be a bit bossy, a bit talkative, a bit shy, a bit crazy. Whatever you want. Just make sure your character is memorable.