Character is half the reason we read. We're excited because of the plot, but we care because of the characters.

Over his own dark Cealdish beard. "Nothing like your marvelous facebear.

When you love something, you have to make sure it loves you back, or you'll bring about no end of trouble chasing it.

You know, I could have carried you.

Also, worldbuilding touches all aspects of your story. It touches plot and character as well. If you don't know the culture your character comes from, how can you know what he's really like? You must know your characters on a much deeper level than you would if you just shrugged your way into a cookie cutter fantasy world.

Did I ever mention I used to be a delivery driver too? I was. I can read a map. What’s more, using a brilliant mixture of zen navigation, Aristotelian logic, and pure rage I can get you your package and/or delicious sandwich relatively close to on-time.

If you're going to have a book full of clever people and nobody ever jokes, it's just not going to ring true to the reader. That said, humor writing is the hardest kind of writing there is.