In the beginning everything is pretty simple - two brothers - Dean, the bad guy, and Sam - the guy who left the family "bussiness" for school, they don't like each other a lot, have a lot of grunts. But they unite in order to find their missing father. With the progression of the series they become best friends, Sam flings to the dark side from time to time and... I won't say no more, I hate spoilers...
Demons, angles, wendigos, strigas, djins, shapeshifters, arachne, banshee, hellhounds, demi-gods - this is just a small, and I mean a small part of what you will encounter and see in this series. If you like this supernatural stuff - watch it! If don't know if you like supernatural creaturs - watch it! There will be blood, gore and death! Peace guys, I'm out!
Sam Winchester: Why'd you let me fall asleep?
Dean Winchester: Because I am an awesome brother. What did you dream about?
Sam Winchester: Lollipops and candycanes.