I'll tell you what an airline pilot told me when I was a student pilot: 1. Never get your heart set on one airline, because it may lead you to having a disappointing career. 2. And never fly for airline "X" because of the planes they fly, that can change. 3. Keep your mind open to all sorts of flying jobs from airlines, cargo, fractional, charter, etc.
But to answer your question: Just like others have mentioned, "character" can set you apart from the guy/gal sitting next to you.
One thing I learned about aviation: A successful career has nothing to do with hard work and determination. It has everything to do with timing and good luck. Some senior captain flying international routes on a large aircraft may end up out of a job when his airline tanks and end up as first officer to some young kid on a RJ; a kid he helped teach how to fly or mentor. It happens.
So, carry a rabbits foot with you.