John Green creates some amazing characters. In all his books, each character has a quirk that makes that character feel real. In Looking For Alaska, his MC, Miles, reads biographies of authors but not the work that they became famous for. He's also obsessed with last words. In An Abundance of Katherines, the MC, Colin, loves anagramming.
I think these character quirks help create interesting characters that feel real and different. His characters aren't run-of-the-mill and they're likable. That is key: to have likable characters.
While I think my MC for COTF is likable, I'm not sure if she stands out enough. I've been having problems trying to make her the main character. The love interest is interesting, but he's not the main character. Elle is obsessed with music but I don't know if that's enough to push her over the edge of interesting. I mean, the story is about her, so she has to be the most interesting person! Or at least likable enough that you care what she has to do and will keep reading.
That's one of the revisions I'm doing right now for COTF. I've still got a lot to do, but at least I'm headed in the right direction.