The picture is heavily based off of 'The Oath of the Horatii' by Jacques-Louis David. I first became acquainted with this story when I took Roman Republic in Livy Book 1.
The Horatii were three brothers who chose to fight so that the Roman army would not have to. Only the youngest survived, and then he went mad and murdered his sister. The specifics kind of deviate from the Sam/Dean air I was trying to create. So, let's just leave it at that.
So there you have it folks, Sam and Dean in Antiquity. It's just regular old graphite and paper. Mostly 2B, I think. I'm not happy with the way Dean turned out, and I blame the scanner TOTALLY. *cough*